the Honda Civic would cost $15 plus $0.50 per mile driven. the Ford Focus would cost $25 plus $0.25 per mile driven. how many miles must you drive for the Honda Civic to be the better option

You can look at it as a equation of cost. Let's assume that X is the distance where both cars have the same costs

For Honda is then $15 + $0.15x

For Ford is then $25 + $0.25x

Let's compare these distances

$15 + $0.15x = $25 + $0.25x

This gives us $0.25x = $10

So x = 40 miles

Honda is cheaper up maximum 40 miles driven. Then Ford becomes cheaper.

m - mile per driven

m = 40

Both of the cars would be the same.