A truck covers a distance of 150 km at a certain average speed and then covers another 200 km at average speed which is 20 km per hour more than the first speed. If the truck covers the total distance in 5 hours, find the first speed of the truck.

Answer

60 km/hr

Explanation

Let the first speed be x km/hr. Then,
`(150)/(x)+(200)/((x+20))=5implies50[(3)/(x)+(4)/((x+20))]=5`
`implies10[3(x+20)+4x]=x(x+20)impliesx^(2)-50x-600=0.`