For this, in basic terms, is asking for the two areas, of each shape, and then add those two together.
So, for the square:
A = Length • Width
A = 8•8
A = 64
Then, for the triangle:
A = 1/2 • Base • Height
A = 1/2 • 6 • 8
A = 3 • 8
A = 24
Finally:
64 + 24 = 88
The final answer is 88 ft^2
Hopefully this helped!