To find the area of a rectangular prism multiply length by width by height.
If the problem has a variable take the two other dimensions and multiply them together. Then take that number and subtract it from the total to find the number that the variable equals.
Hello!
You have to find the area of the prism and the pyramid
rectangular prism is lwh
Put in the values you know
15 * 5 * 7 = 525
For a prism you use

Put in the values you know

Multiply
975/3
Divide
325
Add the values you know
325 + 525 = 850
The answer is D)

Hope this helps!
-x^2 + 7 is the simplified expression