Question

68 miles to 42.5 miles

Answer 1

1) subtract 42.5 miles from 68 miles to find the gross change in distance:  It is 25.5.  Since this is a decrease, write -25.5 miles.
2) divide -25.5 miles by the original distance, 68 miles:
     -0.375
3) multiply this by 100% to find the percentage decrease:
     -37.5% (answer)