we know that
surface area of the figure=surface area rectangular prism+surface area triangular prism
surface area rectangular prism=2*[12*6]+2*[16*6]+[16*12]---> 528 ft²
surface area triangular prism=2*[12*8/2]+2*[16*10]----> 416 ft²
surface area of the figure=528+416-----> 944 ft²
the answer is
944 ft²