Question is below (wasn't sure about the answer)

Answer: Choice A)
[tex]H = \frac{SA}{2(L+W)} - \frac{LW}{L+W}\\\\[/tex]
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Work Shown:
[tex]SA = 2(LW + LH + HW)\\\\2(LW + LH + HW) = SA\\\\LW + LH + HW = \frac{SA}{2}\\\\LH + HW = \frac{SA}{2} - LW\\\\H(L + W) = \frac{SA}{2} - LW\\\\H = \frac{\frac{SA}{2} - LW}{(L + W)}\\\\H = \frac{SA}{2(L+W)} - \frac{LW}{L+W}\\\\[/tex]
This is not the only way to solve for H.