Answer:
41+84=125 so therefore your answer is 125.
This is because simplifying the equation before solving it will lead you to the answer at a much faster rate. For example, in the given equation, the long way would be to distribute 2 to (x+3). Then, you transpose them and combine like terms. Until you get to x + 3 = 8. But if you simplify it first, you will see that it is straightforward. It will lead you to the answer right away which is x + 3 = 8. It saves you from the hassle of doing more algebra :)
Since the length is 15, and the width would be 15, you need to first do 15 x 15.
15 x 15 = 225
Multiply the 6 faces.
225x6
Your final answer would be 1,350.