Alright, let's convert to decimals for these calculations: fractions could get messy.
1/5 = .2
1/2 = .5
Imagine a rectangular solid in your mind. How many sides does it have?
6. In the image shown you have 3 facing you. In addition to those, there are 3 not shown. They will correspond to the calculations you make on the front, though, so all you have to do is double the values you get.
Area is length * width, or length * height, or width * height. So:
A = 3.2 (length) * 4.5 (height) for the front face of the rectangular solid(as well as the back face.)
A = 5 (width) * 4.5 (height) for the right face of the rectangular solid (and the one on the left, away from you.)
A = 3.2 (length) * 5 (width) for the top of the solid(and the bottom).
Calculating these values, we get that
A=14.4
A=22.5
A= 16
So that's 3 out of 6 values for the full surface area.
Like I said though, these values can merely be doubled for the complete area.
Add these three together:
14.4+22.5+16=52.9
multiply by 2 to account for the other 3 sides
52.9 * 2 = 105.8
105.8 is the surface area.
