the distance from city a to city b is 150 miles . while driving from city a to city b , cara drives at a constant speed of 30 miles per hour . dan leaves city a 90 minutes after cara . what is the minimum constant speed in miles per hour that dan must exceed in order to arrive in city b before cara ?
"the time it takes cara to drive to city b is 150 / 30 = 5 hours . dan needs to take less than 3.5 hours for the trip . dan needs to exceed a constant speed of 150 / 3.5 = 42.85 miles per hour . the answer is a ."
divide(150, subtract(divide(150, 30), divide(90, 90)))