To find the area of a circle, you do π × diameter (in this case 10). They have told you to use 3.142 as π, so you do 3.142 × 10 = 31.42. Because it's a semi-circle, you need to halve 31.42 to get 16.21, which is the answer
54=.9x Solve for x. x=54/.9=60
