Answer :

Ratio and proportion

45mi/60%=x miles/100%
cross multiply
60x=4500
   x=75 miles

hope this helps
60% is the same thing as 6/10, or 3/5. So 45 miles is 3/5 of his trip. 45=3/5x, where x is the number of miles in his trip. Divide both sides by 3/5 and you should get 75 miles.