Question

Frank builds kitchen cabinets. He offers four different wood finishes. 1⁄8 of his customers choose dark walnut; 2⁄5 choose golden oak; and 3⁄10 choose cherry. The rest of the customers prefer a natural finish. What fraction of the customers choose the natural finish?

Answer 1

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

Answer 2

7/40 of Franks customers chose the natural finish.