Linear combination of normal random variables

Let $X$ and $Y$ be independent normal random variables with $\operatorname{E}(X) = 15$, $\operatorname{E}(Y) = 25$, $\operatorname{Var}(X) = 16$ and $\operatorname{Var}(Y) = 9$.

Let $Q$ be the random variable such that $Q = cX + 2Y$.

Given that $\Pr(Q > 112.2) = 0.1$, the value of $c$ is closest to