AMC 12 2014b Problem 20

For how many positive integers $x$ is $\log_{10}(x-40) + \log_{10}(60-x) < 2$ ?

$\textbf{(A) }10 \textbf{(B) }18 \textbf{(C) }19 \textbf{(D) }20 \textbf{(E) }\text{infinitely many}$