AMC 8 2008 Problem 5

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? $\textbf{(A)}\ 15 \textbf{(B)}\ 16 \textbf{(C)}\ 18 \textbf{(D)}\ 20 \textbf{(E)}\ 22$