Point $\blue{A}$ is at $\blue{(-1, 8)}$ and point $\purple{M}$ is at $\purple{(3, 5.5)}$. Point $\purple{M}$ is the midpoint of point $\blue{A}$ and point $\green{B}$. **What are the coordinates of point $\green{B}$?**  $($[[☃ numeric-input 1]], [[☃ numeric-input 2]]$)$