The distance from City A to City B is 120 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?  Choose the correct choice
A) 42
B) 44
C) 46
D) 48
E) 50
The time it takes Cara to drive to City B is 120 / 30= 
<gadget id="calculator">120 / 30</gadget>
<output>4</output>
4 hours.   Dan needs to take less than 2.5 hours for the trip.   Dan needs to exceed a constant speed of  120 / 2.5= 
<gadget id="calculator"> 120 / 2.5</gadget>
<output>48</output>
48 miles per hour.   The answer is 48.
<result>D</result>
The distance from City A to City B is 120 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?