This lesson is about applications of percents. Taxes, tips, commissions, percent of change.

1. Skill 10 Ratios and Percent Problems pages 80 and 14-31.

3. Two ways are shown to solve this problem. It is solved by the percent Box
Method on the right and by proportions on the left. Both work just fine.

5. Discounts and taxes
A sweater is on sale at Target for 25% off. If the regular price is $14, find the sale price.
Find 25% of 14 or 0.25 X 14 which is $3.50. Then subtract 3.5 from 14 to find the sale
price. 14.00 – 3.5 or 10.5 So the sale price is $10.50.
If the tax rate is 10%, find the amount of tax on the $10.50 purchase.
Find 0.10 X 10.50 or 1.50 So the tax is 1.50.
Now find the total checkout amount by adding the price of the sweater to the tax.
10.50 + 1.50 or 12.00 So, at the checkout the total amount due is $12.00.
Big idea: Find the percent of discount. Subtract it from the original price.
Find the tax on the discounted price. Add the tax to the discounted price for the
final amount due.
You do this all the time at the store!!

6. Tax and Tips
You buy a sit-down meal at a restaurant (remember those days!) and the meal costs
$25.00. You got really good service so you want to leave a tip for the server.
You decide to leave a 10% tip. How much is the meal before tax?
Find 10% of 25.00 0.10 X 25 or 2.50 Leave a tip of $2.50
Some people figure the tip before the tax. That is what we will do here.
So, how much is the total bill if the tax is 5%?
So far you owe 25.00 + 2.50 or 27.50. Find 5% of 27.50 or 0.05 X 27.50
or 1.38 rounded up.
The total bill is 27.50 + 1.38 or $28.85.

7. Commissions
Some people work on commission. That is their pay is a percentage of the total
Amount they sell.
Jocelyn sells refrigerators at a big box store where she works on commission of 12%.
If she sells $3000 worth of refrigerators in a week, how much is her commission?
Find 12% of 3000. 0.12 X 3000 or 360 So, Jocelyn earns $360 that week.

8. Markup
A store owner pays for the items she sells in her store by paying the manufacturer
what we call “cost.” She then turns around and marks up the price before she
puts out the items for sale to you. The amount of the mark up is her profit—what
she uses to pay the rent, salaries of the workers, profits, etc.
Suppose you own a store and buy $2.00 socks to sell
In your store. The $2.00 is your cost. Before you put them out for sale, you “mark
up” the price 40%. How much do you add to the $2.00?
What is the price of the sock after the mark up?
Find 40% of 2.00 to find the amount of the mark up. 0.40 X 2.00 or 0.80.
You then find the selling price of the socks by adding the cost to the markup.
So 2.00 + 0.80 or $2.80 Sell the socks for $2.80.

9. PerCent of Change
Then change the result to a percent by multiplying by 100.
Find the percent of change for a change of 58 to 95. (Think it’s increasing).
Find the percent of change from 52 to 9. Think: it’s decreasing.
From page 21.
(52-9) then divide by 52. 41/52 or 0.85 Then change to % by multiplying
By 100. Get 85% decrease.

10. Simple Interest I = P r t Interest = Principal times rate as decimal times time in yrs.
Find the simple interest on $42,200 at 8% interest for 2 years. Then find the
ending balance by adding the interest to the original amount.

11. There are lots of practice
problems in your book
with answers. Try them.