Sarah is trying to run a certain number of miles by the end of the month. If Sarah is 80% of the way to achieving her goal and she has already run 40 miles, how many miles is she trying to run by the end of the month?

50 miles

Step-by-step explanation:

Let the miles that she is trying to run by the end of the month be denoted by x.

Since she is 80% of the way to achieving her goal and she has already run 40 miles. This can be expressed as:

80% of x = 40

80/100 × x = 40

0.8x = 40

x = 40/0.8

x = 50

The miles that she is trying to run by the end of the month is 50 miles.