Question 596019
d = rt


60 = 40t


60/40 = t


3/2 = t


t = 3/2


t = 1  1/2


So it will take <img src="http://latex.codecogs.com/png.latex?\Large 1 \frac{1}{2}" title="x" /> (one and a half) hours. This is equal to 90 minutes.