Calculate the Iterated Integral $$\int _ { 1 } ^ { 4 } \int _ { 0 } ^ { 3 } ( 3 + 4 x y ) d x d y$$

Calculate the iterated integral.
$$\int _ { 1 } ^ { 4 } \int _ { 0 } ^ { 3 } ( 3 + 4 x y ) d x d y$$