Charlie finished 7 laps around the track, This is 20% of the number of laps he has to do. How many laps must he do?

1 Answer
Jan 2, 2017

$\text{Target lap count is } 35$

Explanation:

Let the target lap count be $x$

Then 7 laps = 20% of $x$

$7 = \frac{20}{100} x$

but $\frac{20}{100} = \frac{1}{5}$

$7 = \frac{x}{5}$

Multiply both sides by 5

$7 \times 5 = x \times \frac{5}{5}$

But $\frac{5}{5} = 1 \text{ and } 7 \times 5 = 35$

$35 = x$

$x = 35$