Start from

It may be useful to multiply the whole expression by 2, in order to get rid of denominators:

Distribute the negative sign in the left hand side:

Move all terms involving x to the left, and all constants to the right:

Sum like terms:

DIvide both sides -5:

Answer:
194.8 miles
Step-by-step explanation:
510 - 315.2 = 194.8
Hope this helps!