Aja and Emilie were riding their skateboards. They knew that they could ride $3$ miles in $20$ minutes.

1. How far can the girls ride in $45$ minutes?

   Step 1 (a):

   Set up a proportion.

   $\frac{3}{20}=\frac{\it y}{45}$

   Step 2 (a):

   $20y=135$

   Answer (a):

   $y=6.75$ miles

2. If $y$ represents the distance in miles and $x$ represents the time in minutes, write an equation to represent the distance traveled for any time.

   Hint (b):

   You can also use a proportion for this problem.

   $\frac{3}{20}=\frac{\it y}{\it x}$

   Multiply both sides by $x$ to simplify the equation.