The formula for area of a circle is pi r^2. Circle A= pi a^2 Circle B= pi b^2
Now if the area of circle B is 36 times greater than the area of circle A, we can translate than into: areaB=36*areaA pi b^2 = 36 pi a^2 pi b^2 = 36 pi 12^2 (sub in variables) b^2 = 36*12^2 (divide pi from both sides) b^2 = 36 * 144 (solve 12^2) b^2 = 5184 (simplify right hand side) b = 72 (take square root on both sides) Your answer is 72.
