Well is not 21 if you add 9+10 =19
You would take 3.14 and multiply it by 3^2.
The answer is 28.3.
Answer is 4 and 3
<span>
3^2 = 7(3) - 12
9 = 21 - 12
9 = 9
</span>4^2 = 7(4) - 12
16 = 28 - 12
16 = 16<span>
</span><span>
</span>
Z would equal 2 hope this helps!!