In a recent basketball game, Shenille attempted only three-point shots and two-point shots.  She was successful on $20\%$ of her three-point shots and $30\%$ of her two-point shots.  Shenille attempted $30$ shots.  How many points did she score?
$\textbf{(A)}\ 12 \qquad\textbf{(B)}\ 18  \qquad\textbf{(C)}\ 24 \qquad\textbf{(D)}\ 30 \qquad\textbf{(E)}\ 36$
Let the number of attempted three-point shots be $x$ and the number of attempted two-point shots be $y$.  We know that $x+y=30$, and we need to evaluate $3(0.2x) + 2(0.3y)$, as we know that the three-point shots are worth $3$ points and that she made $20$% of them and that the two-point shots are worth $2$ and that she made $30$% of them.
Simplifying, we see that this is equal to $0.6x + 0.6y = 0.6(x+y)$.  Plugging in $x+y=30$, we get $0.6(30) = \boxed{\textbf{(B) }18}$