(a)
12+0.72(8)
12+5.76
17.76 qts of antifreeze
(b)
100(12+8(.72))/(12+8)
100(12+5.76)/20
100(17.76)/20
5(17.76)
88.8%
The area of a circle is area = pi x r^2
The full area = 3.14 x 20^2 = 1256 square feet.
The corner forms a 90 degree angle so the dirt area is 3/4 of a full circle.
Answer = 1256 x 3/4 = 942 square feet