First lets find the are of the base that can be obtaine multiplying 12 times 8.
Area Base = 12*8 = 96
The top rectangle's area can be found by multiplying 13 times 8
Area Top rectangle = 13*8 = 104
The triangles both can be found by multiplying 5 times 12 and then dividing by 2
Area Triangle = (5*12)/2 = 30
*Since there are 2 triangles we multiply 30 times 2 (30*2=60)
And finally the area of the smaller rectangle can be obtained by multiplying 5 times 8
Area small rectangle = 5*8 = 40
To find the surface area we need to add all the values together
Surface area= 96+104+60+40 = 300
ANSWER: 300 feet