Disclosure TC14 Math

A hiker walked for two days. On second day the hiker walked 2 hours longer and at an average speed 1 mile per hour faster than he walked on the first day. If during the two days he walked a total of 64 miles and spent a total of 18 hours walking, what was his average speed on the first day?

a)2mph b)3 c)4 d)5 e)6

簡単に解けるだろうともって取り組んでみたところ、お手上げ問題でした。宜しくお願いします。