Okay. fist off don't think of them as 5 units each, but 1. so if you were to put it on graphing paper and box squares each time. you would be able to get 8 in for both sides to make a square. Area then would be 1600ft squared because 8 ×5 is 40 and 40×40 is 1600. then you calculate how many squares you used. 8×8=64. and 80-64=16 so 16 pieces are left over. then 9×9 (increasing the square) is 81. so 17 pieces to increase it.
5w + 9z = 2z + 3w
Move terms with w to the left - subtract 3w from both sides
2w + 9z = 2z
Subtract 9z from both sides
2w = -7z
Divide both sides by 2
w = 
If the sum of their lengths is 5,520 miles then River D is 2360 and River C is 3160
That easy 56.8.895 because when u add all the steps u find u answer so don’t let it fool u
Surface area of the the rectangles:
8 * 5 + 8 * 4 + 8 * 3 = 96
Surface area of the two triangles:
Use bh/2 base time height over 2
(4 * 3)/2 = 6
There are 2 triangles, 2 * 6 = 12
12 + 96 = 108