Word Problems and Modeling
A free Pre-Algebra lesson from the “Cumulative Review and Test Prep” unit, with a worked example and practice problems including step-by-step solutions.
Word problems become easier when you identify the unknown, choose a variable, and translate each phrase into math. After solving, check the answer in the story, not just in the equation.
What you'll learn
- Translate words into expressions and equations
- Choose operations from context
- Check whether an answer makes sense
Worked example
Problem. A movie ticket costs 9 dollars. You buy a ticket and a snack. The total is 15 dollars. How much was the snack?
- Let s be the snack cost.
- Write 9 + s = 15.
- Subtract 9 from both sides: s = 6.
Answer: 6 dollars
Practice problems
1. A notebook costs 4 dollars and a pen costs 2 dollars. What is the total?
Show solution
- Warm-up: First identify exactly what the question is asking: A notebook costs 4 dollars and a pen costs 2 dollars. What is the total?
- Choose the operation or relationship that matches the wording, then carry it out one clear step at a time.
- Add the two costs.
- 4 + 2 = 6.
- Check the result by substituting or estimating: the response should match 6 and make sense in the original problem.
Answer: 6
2. Mia has 18 cards and gives away 7. How many remain?
Show solution
- Warm-up: First identify exactly what the question is asking: Mia has 18 cards and gives away 7. How many remain?
- Choose the operation or relationship that matches the wording, then carry it out one clear step at a time.
- Giving away means subtract.
- 18 - 7 = 11.
- Check the result by substituting or estimating: the response should match 11 and make sense in the original problem.
Answer: 11
3. The phrase '5 more than x' means...
Choices: x + 5 · x - 5 · 5x · x/5
Show solution
- Warm-up: First identify exactly what the question is asking: The phrase '5 more than x' means...
- For data questions, identify what each statistic measures before calculating so the result matches the question.
- More than means addition.
- 5 more than x is x + 5.
- Verify the selected choice by checking that it satisfies the original prompt and that the other choices fail the same test.
Answer: x + 5
4. A class has 6 tables with 4 students at each table. How many students are there?
Show solution
- Core Practice: First identify exactly what the question is asking: A class has 6 tables with 4 students at each table. How many students are there?
- Choose the operation or relationship that matches the wording, then carry it out one clear step at a time.
- Each table has 4 students.
- 6 x 4 = 24.
- Check the result by substituting or estimating: the response should match 24 and make sense in the original problem.
Answer: 24
5. A bill of 45 dollars is split equally among 5 people. How much does each person pay?
Show solution
- Core Practice: First identify exactly what the question is asking: A bill of 45 dollars is split equally among 5 people. How much does each person pay?
- Choose the operation or relationship that matches the wording, then carry it out one clear step at a time.
- Split equally means divide.
- 45 divided by 5 equals 9.
- Check the result by substituting or estimating: the response should match 9 and make sense in the original problem.
Answer: 9
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