Question

Please let me know the solution to this question

Answer 1

1. Let V km/hr be the initial speed of car

time taken to travel 72 km is equal to. t1 = 72/V

2. the increased velocity be V+10 km/hr

time taken to travel 72 km is. t2= 72/ ( V +10)

Given difference in time is 36 min = 36/60 hr

so, t1-t2= 36/60

$( \frac{72}{v}) - ( \frac{72}{v + 10} ) = \frac{36}{60}$
By solving we get,

v^2+10v-1200=0

v= -40,30
v not be negative, so v= 30km/hr

Any doubts comment :) ;)