So to do this one, you have to do the problem backwards!
The equation looks like this with everything plugged in:
272.2 = 2(3.14)r
You are looking for r, so start dividing
272.2 = 2(3.14)r
136.1 = (3.14)r
43.3 = r
Therefore the radius is about 43.3 in.
I hope I helped!
For question 22, divide each number by 1.41 to see which one produces a quotient larger than 0.9. d is the answer.
For #23, multiple 0.155 million by 86%, the result is 133,300
again, d is the correct answer.