Find the area of the green polygon

The area bounded by the points

(0,0)

(18,3)

(24,12)

(12,15) and

(3,9)

=0.5x{18x12-24x3+24x15-12x12+12x9-15x3}

=211.5

$A_1=\text{trapezoid}=\dfrac{1}{2}(3+12)(6)=45$

$A_2=\text{triangle}=\dfrac{1}{2}(3)(9)=13.5$

$A_3=\text{triangle}=\dfrac{1}{2}(3)(12)=18$

$A_4=\text{trapezoid}=\dfrac{1}{2}(3+12)(6)=45$

$A_5=\text{triangle}=\dfrac{1}{2}(3)(18)=27$

$A_{green}=15(24)-45-13.5-18-45-27=$ $\boxed{211.5}$