AoPS Wiki:Problem of the Day/June 30, 2011
If 
, then which expression is equivalent to 
?
$\text{(A)}\ b^2-12a \qquad \text{(B)}\ b^2-15a^2 \\ \text{(C)}\a^2-9b \qquad \text{(D)}\ a-16b \\ \text{(E)}\ a^2-18b$ (Error compiling LaTeX. Unknown error_msg)
