For the surface area, you need to add up the area of all sides, six in this example, but it can be simplified into three by multiplying some of them by two as its presumed a rectangle
x1 = 5*14*2 = 140
x2 = 16*14*2 = 448
x3 =16*5*2 = 160
You find the sum of these; 140 + 160 + 448 = 300 + 448 = 748
