To draw the 2 dimensional representation, we just "open" the box and flatten it. Once we have it opened, we find the area of each side and add them up for the total surface area. See the pic. Let me know if you have questions. :)
The sum is adding
3 times a number is 3x
And 15 is +15
3x+15
Answer:
it is 81 with doing some simple math
Answer:
B and R
I think that is the name of the lines. If not the the first two lines!!!!
Answer:

Step-by-step explanation: