AMC 8 2012 Problem 9

The Fort Worth Zoo has a number of two-legged birds and a number of four-legged mammals. On one visit to the zoo, Margie counted 200 heads and 522 legs. How many of the animals that Margie counted were two-legged birds? $\textbf{(A)}\hspace{.05in}61 \textbf{(B)}\hspace{.05in}122 \textbf{(C)}\hspace{.05in}139 \textbf{(D)}\hspace{.05in}150 \textbf{(E)}\hspace{.05in}161$