You do the sum(40) subtracted by 8, the answer from that divided by 2 since Erin's two times younger. 40-8=32 32÷2=16 Then if you want to check it you do the opposite and get the same sum(40) so 16×2=32 and 32+8=40
The answer is B. To find the Circumference (what you're looking for) you use 2×pi×radius. Which is 2×pi×7. In terms of pi that's just 2×7, which equals 14. So that means your answer is 14pi.
