A pair of shoes costs $80. It is on sale for 25% off. What is the… Step by Step

Step by step

The question

Question: A pair of shoes costs $80.

It is 25% off.

What is the sale price?

There are four choices.

First we solve it, the normal way.

Then we pick.

1 Find the discount

Percent means out of 100.

So 25% is 25 divided by 100: 0.25.

The point moves 2 places to the left.

25% = 25 ÷ 100 = 0.25

The discount is 25% of $80.

"Of" means times: 0.25 times $80.

To multiply decimals: first 25 times 80, as whole numbers.

That is 2000.

Then count the decimal places: 2, the digits after the point in 0.25.

So it is 20.00.

25 × 80 = 2000

2 decimal places: 20.00

So the discount is $20.

discount = 0.25 × $80 = $20

Careful!

The discount is the money we save.

We still pay the rest.

Careful: $20 is what we save, not what we pay

2 Take it off

A discount comes off the price.

$80 minus $20 is $60.

sale price = $80 − $20 = $60

So the sale price is $60.

3 Check

Let's check another way: we pay 100% minus 25%: 75% of the price.

0.75 times $80 is $60.

The same.

So the answer is right!

100% − 25% = 75%: 0.75 × $80 = $60

4 Pick the choice

Our answer is sale price: $60.

That is choice C.

C) $60

5 Why not the others

A is $20.

Wrong: that is only the discount.

That is the Careful mistake from before.

A) $20 ✗ that is only the discount

B is $55.

Wrong: took $25 off: 25% of $80 is $20, not $25.

B) $55 ✗ took $25 off: 25% of $80 is $20, not $25

D is $100.

Wrong: added the discount instead of taking it off.

D) $100 ✗ added the discount instead of taking it off

Let's look back.

First: find the discount.

Then: take it off.

Then: check.

Then: pick the choice.

Last: why not the others.

Answer