Truck P and Truck Q drive on the highway in the same direction at respective rates of 70 kph and 75 kph. If Truck Q is 4 km behind Truck P, by how much does Truck P need to increase the speed to catch up with Truck P in 20 minutes?  Choose the correct choice from the following choices
A) 4 kph B) 5 kph C) 6 kph D) 7 kph E) 8 kph
Truck Q needs to gain 4 km in 20 minutes.   The relative speed difference needs to be 4 km / 20 minutes = 12 km/hour   Truck Q needs to increase up to 82 kph, thus an increase in 7 kph.   The answer is 7 kph.
<result>D</result>
Truck P and Truck Q drive on the highway in the same direction at respective rates of 70 kph and 75 kph. If Truck Q is 4 km behind Truck P, by how much does Truck P need to increase the speed to catch up with Truck P in 20 minutes?