Two cars start at the same time from opposite ends of a highway that is 105 miles long. One car is riding at 15 mph and the second car is riding at 20 mph. How long after they begin will they meet? Choose the correct option:
A) 1
B) 2
C) 3
D) 4
E) 5
As cars are moving in opposite directions their speeds will be added. So their relative speeds: 20+15= 
<gadget id="calculator">20+15</gadget>
<output>35</output>
35 mph   Total distance to be covered= 105 miles.   Time taken would be: 105 miles/35 mph = 3 hours   3 is the answer.
<result>C</result>
Two cars start at the same time from opposite ends of a highway that is 105 miles long. One car is riding at 15 mph and the second car is riding at 20 mph. How long after they begin will they meet?