If a car travel at an average speed of 80 km per hr for 20 min, and then slowed down to an average speed of 50 km per hr over the next 15 min. How far would it travel in total?

80 km/h*(1/3 h) + 50 km/h*(1/4 h)

= 80/3 + 50/4 km
= 39.17 km