Answers:
A) 2,600 cubes (13 x 40 x 5 = 2,600)
B) 6,600 cubes (11 x 20 x 30 = 6,600)
C) Boxes A and C or boxes B and C
D) 11,200 cubes (13 x 40 x 5) + (11 x 20 x 30) + (8 x 10 x 25) = 11,200
Hey There!
Let's setup.
5x+13 = 12x-8
Subtract 5 as it is lower.
12x - 5x =7x
We now have 7x-8=13
Add 8 on both sides.
13 + 8 = 21
We now have 7x = 21
Divide 7 from both sides.
21/7= 3
Therefore, x would equal to 3.
Hope this helped!