Answer
$A=\frac{5}{2}h^2+\frac{3}{2}h$
When the height is 6 cm: 99cm
Work Step by Step
Define: Let h = The height. Let b= the base.
Write: $b=5h+3$
Formula for the area of a rectangle: $A=\frac{1}{2}bh=\frac{1}{2}(5h+3)h=\frac{5}{2}h^2+\frac{3}{2}h$
When the height is 6 cm: $A=\frac{5}{2}h^2+\frac{3}{2}h=\frac{5}{2}6^2+\frac{3}{2}6=99$
