Seventh Grade · Math · week 5

Tax, tip, and discount

Apply percent increase and decrease to real purchases: sales tax, tips, and discounts.

Sales tax and tips are percent INCREASES added on top of a price: total = price x (1 + tax rate) or price x (1 + tip rate). A discount is a percent DECREASE: sale price = original price x (1 - discount rate).

The trick is always the same one from last week -- turn the percent into a multiplier first, then multiply. Read carefully to tell whether a rate is being added (tax, tip) or subtracted (discount, sale, off).

📋 For the teacher
Teach it (10–15 min):
  • Sort every problem first: is this rate ADDED (tax, tip) or SUBTRACTED (discount, off, sale)? Getting that right is most of the battle.
  • Practice the multiplier shortcut every time: 8% tax is x1.08; 25% off is x0.75.
  • Model rounding money to the nearest cent, and be clear that $26.875 rounds up to $26.88.
  • Use a real receipt or menu to price out a tax-and-tip problem together.
Talk about it:
  • How do you decide whether to add or subtract a percent in a money problem?
  • Why does 8% tax turn into the multiplier 1.08?
  • How would you find the original price if you only knew the sale price and the discount percent?

Mastery looks like: They correctly compute tax, tip, discount, or an unknown discount percent, choosing the right multiplier and rounding money correctly.

Common stumbles: Adding a discount rate instead of subtracting it (or the reverse for tax); rounding money incorrectly.

See it visually

Interactive, spoken-aloud tools that show this idea in motion.

Counting & Ten-FramesCount objects in ten-frames and base-ten blocks, one tap at a time.try →
Homework for this lessonType it, write it with a stylus, or print it for pencil & paper.open →
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