Bill spends two days driving from Point A to Point B . On the first day, he drove 2 hours longer and at an average speed 5 miles per hour faster than he drove on the second day. If during the two days he drove a total of 680 miles over the course of 18 hours, what was his average speed on the second day, in miles per hour?  Options.
A) 20
B) 25
C) 28
D) 30
E) 35

Rationale: first recognize that we have two pieces of information regarding the time bill spent driving each day . on day 1 , bill drove 2 hours longer than he drove on day 2 . so , let x = # of driving hours on day 2 then x + 2 = # of driving hours on day 1 bill drove a total of 18 hours so , x + ( x + 2 ) = 18 simplify : 2 x + 2 = 18 solve , x = 8 so , bill drove 10 hours on day 1 and he drove 8 hours on day 2 now let ' s solve the question by starting with a word equation . let x = speed driven on day 2 so , x + 5 = speed driven on day 1 ( distance traveled on day 1 ) + ( distance traveled on day 2 ) = 680 distance = ( rate ) ( time ) we get : ( x + 5 ) ( 10 ) + ( x ) ( 8 ) = 680 expand : 10 x + 50 + 8 x = 680 simplify : 18 x + 50 = 680 18 x = 630 x = 35 ( mph ) answer : e
Answer: E