Hello
The formula of the total surface area of this figure is

The total surface area of this figure is 20x + 30
The polynomial that represents the total surface area of the figure is
20x + 30.
Now we have to find the surface area of figure a
3 by 5 by 3
The surface area for figure a is

The surface area for figure b is
3 by 5 by 5

The surface area of figure c is
3 by 5 by 12

The surface area for figure d is
3 by 5 by 14

From the calculations above, the surface area of figure a, b, c and d are 78 units, 110 units, 222 units and 254 units respectively