[tex]\sf~SA=2(wl+hl+hw)[/tex]
Plug in what we know:
[tex]\sf~SA=2((4\dfrac{5}{6})(18\dfrac{1}{2})+(5\dfrac{1}{3})(18\dfrac{1}{2})+(5\dfrac{1}{3})(4\dfrac{5}{6}))[/tex]
Multiply:
[tex]\sf~SA=2((89\dfrac{5}{12})+(98\dfrac{2}{3})+(25\dfrac{7}{9})[/tex]
Add:
[tex]\sf~SA=\boxed{\sf213\dfrac{31}{36}}[/tex]
