#### Explanation:

Remember that if there is a 25% discount, then the amount you are paying represents 75%. We know the original price (ie 100%)

There are several methods.
Simplest: Find 25% of the$40 and subtract to find the price to be paid. 25% of 40 = 25/100 xx 40=10 discount price = 40-10 =$30

Second method. Find 75% immediately

75% of 40 = 75/100 xx 40 = $30 You can do any percentage question using the concept of direct proportion. $\frac{40}{100} = \frac{x}{75} \text{ if $40 is 100%, how much is 75%?}$

$100 x = 75 \times 40 \text{ cross-multiply}$

$x = \frac{75 \times 40}{100} \text{ this a possible expression for the sale price}$

x = \$30