Lesson 8.78.7 · Part II
Start hereWords, worked example, and sentence starters
Learning target I can model and solve real-world problems using equations and inequalities.
Start hereWords for this lesson
Read each word before you begin. Say it out loud.
| Word | What it means | Example |
|---|---|---|
| ModelSpanish: Modelar | To show a real-life situation with an equation or inequality. | 'Twice a number is 18' → 2n = 18 — the equation models the words |
| EquationSpanish: Ecuación | A math sentence with an equal sign showing both sides are the same. | x + 8 = 15 — exactly one answer: x = 7 |
| InequalitySpanish: Desigualdad | A math sentence that compares two sides with <, >, ≤, or ≥. | x + 5 > 12 — many answers: x = 8, 9, 10, ... |
| ReasonablenessSpanish: Razonabilidad | Checking if your answer makes sense. | If the problem asks for a number of people and you get x = −3, that is NOT reasonable |
| VariableSpanish: Variable | A letter that stands for a number that is unknown or can change. | “5 less than a number is 12” becomes x − 5 = 12, where x is the variable. |
| ConstraintSpanish: Restricción | A limit in a problem that tells what values are allowed. | “You can spend at most $20” is a constraint: cost ≤ 20. |
Say it and write itSentence starters
Finish each sentence out loud with a partner. Then use them in your writing.
Word bank ModelEquationInequalityReasonablenessVariableConstraint
Watch outA common mistake
A common mistake in Equations and Inequalities Problem Solving is matching the wrong model to a key phrase. For 'the getaway car held no more than 6 bags,' students often write the equation b = 6 instead of the inequality b ≤ 6, because they see one number and assume it must be exact. The same mistake happens in reverse: for 'the reward split equally among 5 people gave each $40,' students sometimes write the inequality 5p ≥ 40 instead of the equation 5p = 40, because 'split equally' sounds like it could mean a range. Before you submit, ask: does this phrase give one exact value (equation, =) or a limit/range (inequality, <, >, ≤, ≥)?
Lesson 8.78.7 · Part II
Apply Day · Version ASupported practice
Learning target I can model and solve real-world problems using equations and inequalities.
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1Complete each step, then write the final answer.
A total divided equally among 2 people gave each person $35. What was the total?
Show your workHint Write t ÷ 2 = 35. Multiply both sides by 2.
Final answer: -
2Complete each step, then write the final answer.
A cup holds at most 8 ounces. It has 5 ounces of juice. How many more ounces can you add at most?
Show your workHint "At most" is a limit. Write 5 + j ≤ 8.
Final answer: -
3Complete each step, then write the final answer.
A total divided equally among 6 people gave each person $9. What was the total?
Show your workHint Write t ÷ 6 = 9. Multiply both sides by 6.
Final answer:
Lesson 8.78.7 · Part II
Apply Day · Version BCore practice
Learning target I can model and solve real-world problems using equations and inequalities.
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1Circle the letter of the best answer. Show how you know.
Which situation needs an inequality, not an equation?
- AA bag can hold no more than 12 apples.
- BEach of 3 boxes holds exactly 12 eggs.
- C12 cookies were shared equally by 4 kids.
- DA pack of 12 pens costs $6.
Show your work -
2Complete each step, then write the final answer.
Each shelf holds 18 books. A library has 250 books. Write and solve an inequality. How many shelves are needed?
Show your workFinal answer: -
3Complete each step, then write the final answer.
A total divided equally among 7 people gave each person $11. What was the total?
Show your workFinal answer:
Lesson 8.78.7 · Part II
Apply Day · ChallengeExtension
Learning target I can model and solve real-world problems using equations and inequalities.
-
1Circle the letter of the best answer. Show how you know.
A school van can carry at most 14 passengers. There are already 9 passengers on board. Let p be the number of additional passengers who can get on. Which inequality models this situation?
- A9 + p ≤ 14
- B9 + p ≥ 14
- C9 + p < 14
- Dp − 9 ≤ 14
Show your work -
2Complete each step, then write the final answer.
A class needs at least $300 for a trip. They earn $12 for each car wash. Kim writes 12c = 300. Lee writes 12c ≥ 300. What is the least number of car washes they need?
Show your workFinal answer: -
3Complete each step, then write the final answer.
A box holds 24 cans. A store has 270 cans to pack. Write and solve an inequality. How many boxes are needed?
Show your workFinal answer: