Two towns are 80km apart. Sylvia wants to drive from one town to the other in exactly one hour. For the first 30minutes she drives at a rate of 60km/h. At what constant rate must she drive for the next 30minutes if she is to accomplish her goal?

100 km/hr

Step-by-step explanation:

First Leg:

Speed = 60 km/h

Time = 30 min = 0.5 h

1st leg distance = speed x time = 60 km/hr x 0.5hr = 30 km

Second Leg:

Distance remaining = 80 km - 30 km = 50 km

Time = 30 min = 0.5 h

speed = distance / time = 50 / 0.5 = 100 km/hr