Question

Mr.Green went for a trip. Twenty percent of his trip he traveled on the bus. How long was Mr.Green's trip, if he covered by bus 15 miles?

Answer 1

The whole journey was 100% 
He traveled part of the journey by bus which was equivalent to 20% of the journey. The distance traveled by bus is 15 miles. Therefore;
  the total distance will be (15/20)×100 = 75 miles
The trip was therefore 75 miles long

Answer 2

Solution: 20% of travel by bus which is equivalent to 15 miles.
   20% of total = 15 miles
 Then, 1% = 15/20
   And, 100% = (15/20) * 100 = 75
   The trip for which Mr. Green went was 75 miles.