So you subtract the fractal amounts from the whole with all of his customer being 1 and adding all the fractions 1-(1/8+2/5+3/10)
1-(1/8+4/10+3/10)
1-(1/8+7/10)
1-(5/40+28/40
1-(33/40)
1=40/40
40/40-33/40
7/40 of his customers chose a natural finish
The second one is the answer
