2 cars $15 plus .50 per mile other car $25 plus .25 per mile how far do you have to drive in each car to pay the same amount

Write the equations for both cars:
Let x= mile
1 st car= $15 x 0.50x
2nd car= $25 x 0.25x

Make them equal to each other to find the mile for both cars to pay the same amount.
Solve:
$15 x 0.50x = $25 x 0.25x
15 x 0.25x = 25
0.25x = 10
X= 40 miles