Question

a car cover a certain distance in 50 mins if it runs at 45 km per hour . how much time will it take to cover the same distance at the speed of 30 km per hour

Answer 1

D = S*T
D = 45 * 50/60...[since T is in mins, convert it into hrs]
    = 3*50/4 = 3*25/2 = 75/2 Km
75/2 = 30 * T
75/2*30 = T
75/60 = T
T = 75/60 hrs or 1 hr 15 mins
T = 75/60 * 60 = 75 mins
So it will take 75 mins.
Hope it helps.