A train traveling at 60 kph covers a given distance in 3 hou

A train traveling at 60 kph covers a given distance in 3 hours. By how many kilometers per hour must its rate be increased so that it will travel the distance in one-half hour less time?

Solution

the distance it covers is the rate*time or 60*3 = 180
so we can use rate*time=distance to determine the rate:
x*2.5hours=180
2.5x=180
x=72 kmh