For W, W = 28B.
Given that one concrete block is 28 pounds, and that B is the number of blocks, we can multiply both values to get the amount of pounds, or weight, of the quantity of B blocks. So W = 28B.
For B, B = W ÷ 28
Now that we know the equation for the weight, W = 28B, we can divide both sides by 28 to isolate the variable, B. The equation now becomes B = W ÷ 28.