ArithmeticTravelling at 4/5th of the usual speed, a man is 15 minutes late. What is his usual time to cover the same distance

Travelling at 4/5th of the usual speed, a man is 15 minutes late. What is his usual time to cover the same distance

Normal speed $\to$ 5

Present speed $\to$ 4

$w h e n d i s \tan c e i s c o n s \tan t s 1 * t 1 = s 2 * t 2 s * t = \frac{4}{5} s * (t + 15) 5 t = 4 t + 60 t = 60 m i n = 1 h o u r$