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Life · Guided lesson

Solve and interpret an inequality

About 11 minutes · 3 reading + 8 practice and checks
Time includes reading, practice, and questions. Extra videos or further study are optional.
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A checked algebra notebook that models four situations, solves equations and inequalities, and tests solutions against the original conditions.

Keep your working files in your own notebook or software. Save a private description, checklist, and work link in My Proof.

What to include

  • Include four clearly defined quantity models with units.
  • Show balanced transformations and distribution in at least one model.
  • State a permitted inequality set and check its boundary.
  • Check each final value in its original relationship.
  • Add all six changed-case responses and explain one infeasible whole-number arrangement.

Review and revise

Use these criteria to check your work and choose what to improve.

  • Method: applies the course-specific rules to the supplied cases with visible intermediate work.
  • Accuracy: results agree with the stated facts, units, boundaries and independent checks.
  • Reasoning: explains why the result follows and identifies a limitation or unresolved question.
  • Transfer: completes changed cases and revises the final project when a relevant assumption changes.
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Before you begin

The idea in everyday life

Original case: A box holds at most 25 tokens. Four labels are fixed and each group adds three tokens: 3x+4 ≤ 25, with x a nonnegative whole number.

The idea

An inequality describes a set of permitted values. Addition and subtraction preserve its direction. Multiplying or dividing by a negative reverses the comparison. A context may further restrict values to whole numbers or nonnegative quantities.

Follow along

Solve and interpret an inequality — worked practice

An inequality describes a set of permitted values. Addition and subtraction preserve its direction. Multiplying or dividing by a negative reverses the comparison. A context may further restrict values to whole numbers or nonnegative quantities.

Original case: A box holds at most 25 tokens. Four labels are fixed and each group adds three tokens: 3x+4 ≤ 25, with x a nonnegative whole number.

Case information

Paste at A1.

ARecordBGiven
Original caseOriginal case: A box holds at most 25 tokens. Four labels are fixed and each group adds three tokens: 3x+4 ≤ 25, with x a nonnegative whole number.

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  1. 1. 1. Isolate the variable expression

    Subtract four from both sides.

    You should see: 3x ≤ 21.

  2. 2. 2. Divide and state the set

    Divide by positive three and include the original whole-number condition.

    You should see: x ≤ 7; permitted groups are 0,1,2,3,4,5,6,7.

  3. 3. 3. Test boundary and violation

    Check seven and eight in the original capacity expression.

    You should see: Seven gives 25 and fits; eight gives 28 and does not fit.

  4. 4. 4. Test a negative coefficient

    Solve −2z < −6 and explain the comparison reversal.

    You should see: z > 3, because division by −2 reverses the inequality.

Now change one thing

Capacity becomes 28 with the same three-token groups and four labels. What is the maximum whole number of groups?

Your work

What to finish

A solution set, boundary tests and negative-coefficient comparison.

Common mistake

Watch for this

The context restricts x to a nonnegative whole number.

How can I tell I understand it?

Distinguish a numerical solution set from feasible group counts and reverse comparisons when dividing by a negative.

Try 3 questions

Quick knowledge check

Answer all 3 questions. Get at least 2 right and the lesson completes automatically.

Not yet passed

You’ll get an explanation for each answer. Signed in? Your results save to your account.

1A 20-token box has two labels and three tokens per group. What is the maximum number of groups?
2Which values solve −3t ≤ −12?
3Why is x=7.5 not allowed in the original box even if a different numerical capacity allowed it?
0 of 3 answeredApply the lesson to a short question, then review the explanation.
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Answer all 3 questions above and get at least 2 right. You can review the explanations and try again.

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Sources and further reading

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OpenStax: linear inequalities
Source & access notes · checked 2026-10-01

Web open/search showed the official page, its topic heading and relevant concept description. This is a content/source check, not a provider endorsement.

Access: Official page retrieved with the web reader on 2026-10-01; interactive tools and videos were not certified by retrieval.

Reuse: Original fictional teaching cases, calculations, questions and examples; link and short factual paraphrase only. No copied source exercises or illustrations.

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