Solution:
Let each cubic block be represented with x
Let each spherical block be represented with y
Let each cylindrical block be represented with z
For A,
3x + y = 2y + z
For B,
3x = 5y
For c,
We want to find 3x + 3y
From
3x + y = 2y + z
3x +y -2y =z
3x-y = z-----------------------(m)
From B,
3x = 5y
Substitute 3x = 5y into (m) above
3x-y = z
5y-y = z
4y = z----------------------------------(b)
From C,
3x + 3y = 5y + 3y = 8y
3x + 3y = 2(4y)
3x + 3y = 2z
Recall, z = cylindrical block
The two blocks that will balance C is cylindrical block
