what is the optimum order size that will minimze storage costs?

y= 1.5x + (200000/ x)

Is y the storage cost? Is x the ordr size?

If so, then set dy/dx = 0 and solve for y.

0 = 1.5 -200,000/x^2
200,000/x^2 = 1.5
x^2 = 133,333
x = 365