S travels with 40 percent of his usual speed and reaches his home 15 minutes late. What is the usual time (in minutes) taken by him to reach home?
Show answer & explanation
Correct answer: A
Explanation
Let the usual time = x minutes
New speed = 40% = 2/5 of the speed
Time = 5/2 × x
Extra time -
= 5x/2 - x
= 3x/2
3x/2 = 15
3x = 30
x = 10 minutes