7th grade · Math · Unit 21 of 22
Tips, Discounts & Interest
Percents in shopping and saving
What your child practices
Your child uses percents to find tips, sale prices and percent discounts, compares two sales, and finds simple interest on savings.
Texas Essential Knowledge and Skills (TEKS) teks student expectation: 7.4(D); 7.13(E); 7.13(F) · percent problems with tips, discounts and sales, and simple interest
How we explain it
Children can open this short lesson before they practice.
- To find a percent of an amount, change the percent to a decimal and multiply.
- A tip is added to a bill; a discount is taken off the price.
- Simple interest = principal × rate × time.
Example: A $40 sweater is 25% off. What is the sale price? 25% of 40 = 0.25 × 40 = 10. 40 − 10 = 30. Answer: $30
Tips, Discounts & Interest in Texas
In the Texas Essential Knowledge and Skills (TEKS), this is unit 21 of 22 in 7th grade Math, after Angle Relationships and before Taxes, Net Worth & Interest.
Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.
Source: Texas Education Agency (TEA)
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
Sam's family has a restaurant bill of $41.00 and leaves a 20% tip. How much is the tip, in dollars?
answer box
8.20
Hint: 10% of $41.00 is $4.10. 20% is double that: $8.20.
Question 2
A pair of shoes regularly costs $106.00. It's on sale for 15% off. What is the sale price, in dollars?
🏷️15% offanswer box
90.10
Hint: Discount: 15% of $106.00 = $15.90. Sale price: $106.00 − $15.90 = $90.10. (Or pay 85%: 0.85 × $106.00.)
Question 3
What is 15% of $50.00?
- $7.50
- $42.50
- $5.00
- $15.00
$7.50
Hint: Start with 10%: move the decimal point one place left to get $5.00. 5% is half of 10%, $2.50. 10% + 5% = $7.50.
Question 4
Two stores sell the same scooter. Which store has the lower sale price?
Store Regular price Sale A $90.00 30% off B $120.00 15% off - Store B
- They cost the same
- Store A
Store A
Hint: Store A: pay 70% of $90.00 = $63.00. Store B: pay 85% of $120.00 = $102.00. Store A is cheaper.
Question 5
Jay puts $1900.00 in a savings account that pays 4% simple interest per year. How much interest will it earn in 2 years?
answer box
152.00
Hint: Simple interest: I = P × r × t = $1900.00 × 0.04 × 2 = $152.00.
Question 6
A backpack regularly costs $19.00. It's on sale for $7.60. What percent is the discount?
answer box%
60 %
Hint: The discount is $19.00 − $7.60 = $11.40. Divide by the regular price: 11.40 ÷ 19.00 = 0.6 = 60%.