we know that
[surface area of the ramp]=10*16+8*16+6*16+2*[6*8/2]
[surface area of the ramp]=160+128+96+48-----> 432 ft²
the answer Part a) is
the surface area of the ramp is 432 ft²
if 1 ft² is sold for--------------------> $3
432 ft²-------------------> x
x=432*3-----> x=$1296
the answer Part b) is
$1296