In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.
Q: Problem: 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
A:
e