Doug C. answered • 10/27/18

Math Tutor with Reputation to make difficult concepts understandable

Hi Amanda,

It would have been easier to see if the book had shown an intermediate step.

The key is that LW = 532, so L = 532/W.

C(W) before substitution results in C(W) = 14W + 28L + 5W = 19W + 28L.

Or, C(W) = 19W + 28(532/W). The key to getting to the equation showing in the book is that 19 divides 532 evenly, so this could be written as C(W) = 19W + 28(19)(28)/W. Then the "book" factors out the 19, giving C(W) = 19 (W + 28(28)/W), But 28(28) = 784, so that is where the 784 came from.