We will first evaluate the inner most integral, ${\displaystyle \underset{1}{\overset{2}{}}}(x+6y)dx.$ Note that we are integrating with respect to $x,$ and treating $y$ as a constant.

${\displaystyle \underset{1}{\overset{2}{}}}(x+6y)dx=[\frac{1}{2}{x}^2+(x)xy]{|}_1^2||$

$=\frac{3}{2}+(,x$ Your answer cannot $be$ understood $or$ graded. More Information $)y$