Question

what is
40π=5⁄18πr2
(5/18 is a fraction and 2 is an exponent)

Answer 1

r1 = -12 and r2 = 12

Answer 2

$\bf 40\pi =\cfrac{5}{18}\pi r^2\implies 40\pi =\cfrac{5\pi r^2}{18}\implies 720\pi =5\pi r^2\implies \cfrac{720\pi }{5\pi }=r^2 \\\\\\ 144=r^2\implies \sqrt{144}=r\implies 12=r$