选择题
2008 AMC 8 Problem 5: Palindrome Odometer
Barney Schwinn notices that the odometer on his bicycle reads 1441, a palindrome, because it reads the same forward and backward. After riding 4 more hours that day and 6 the next, he notices that the odometer shows another palindrome, 1661. What was his average speed in miles per hour?
A.
15
B.
16
C.
18
D.
20
E.
22