The formula to find surface area is SA= 2(L×W + L×H + H×W)
The 2 is there to double each side.
so..
A)
SA = 2(L×W + L×H + H×W)
= 2( 16×9 + 16×4 + 4×9)
= 2( 144 + 64 + 36)
= 2( 244)
= 488 units2
B) SA = 2(L×W + L×H + H×W)
= 2 ( 13×9 + 13×4 + 4×9)
=2 ( 117 + 52 + 36)
=2 ( 205)
SA= 410cm2
