Math 7 · Unit 2, Lesson 3
Tax, Tips, and Fees
Tax, tips, commission, and fees.
I say it the way your test says it.
And I say it the way you would say it to a friend. Same idea, two ways.
Write it down. Do every step on paper, one line per step. Percent problems go wrong in your head, not on the page. If you changed something, it should be on the paper.
Go in order. Each tile has a short explanation, then a "Let me try a few" button.
When you have finished
At the end of each tile you will find a review form to give us feedback.
NC standards: NC.7.RP.3.
Words we use
| Word | Plain English | What you do |
|---|---|---|
| Sales tax | Money added to a price that goes to the government. | Multiply the price by 1 plus the rate: 1.07 for 7 percent. |
| Tip | Extra money you give for good service. | Find 10 percent, then build to the tip you want. |
| Fee | A charge added on. | Same as tax: multiply by 1 plus the rate. |
| Commission | The share of a sale a salesperson earns. | Multiply the sales by the rate. It is not added to the price. |
| Total | Everything you pay. | Price plus tax, tip, or fee. |
| 107 percent | The price plus 7 percent. | One multiplier, 1.07, does both steps. |
The big idea
A proportional relationship always multiplies by the same number, the unit rate.
Percent means out of 100. A percent is a unit rate for 100 instead of for 1: 30 percent means 30 for every 100.
This lesson added percents on top of a price. Tax, tips, and fees are added to what you pay, so the total is more than 100 percent of the price: 100 percent plus 7 percent is 107 percent, and one multiplier, 1.07, does the whole job. Tips are built from 10 percent in your head. Commission is different: it is a share of the sale paid to the salesperson, and the customer does not pay extra.
Exit ticket
On paper or an index card. Use the math word and the plain-English word.
- A meal costs $24. You leave a 15 percent tip. How much is the tip, and what is the total?
- What one number do you multiply a price by to add 7 percent tax?
- A salesperson earns 5 percent commission on $1,200 of sales. Does the customer pay extra?
Check your exit ticket
- The tip is $3.60 and the total is $27.60.
- 1.07.
- No. The salesperson earns $60 out of the $1,200.
Printables
A one-page study guide with Elle and Finn, the two big-idea sentences, the 107 percent idea, the tip shortcut, and the commission warning. Plus a worksheet with an answer key and a lesson plan that walks a parent or tutor through the three tiles.
Where this goes next
NC Grade 7 standards in this lesson: NC.7.RP.3.