Step-by-step explanation:
[tex] \frac{1}{2} (11ft + 17ft) \times 12ft \\ \frac{1}{2} \times 28ft \times 12ft \\ divide \: 28 \: by \: 2 \\ 14ft \times 12ft = 168 {ft }^{2} \\ answer = 168 {ft}^{2} [/tex]
