Answer:
[tex]h = 12m \\ ( b)_{1} = 21m \\ ( b)_{2} = 15m[/tex]
Now lets find the area
[tex]area = \frac{1}{2} h( b_{1} + b_{2}) \\ = \frac{1}{2} \times 12(21 + 15) \\ = \frac{1}{2} \times 12 \times 3 6 \\ = \frac{12}{2} \times 36 \\ = 6 \times 36 \\ = 216[/tex]
