The area of the irregular figure will be equal to the sum of area of triangle and the area of the rectangle.
The required area can be determined as,
[tex]\begin{gathered} A=A_t+A_r \\ =(\frac{1}{2}\times8\text{ ft}\times9\text{ ft)+(15 ft}\times26\text{ ft)} \\ =36ft^2+390ft^2 \\ =426ft^2 \end{gathered}[/tex]Thus, the required area of the irregular figure is 426 square feet.