The balloon has a volume
dependent on its radius
:

Differentiating with respect to time
gives

If the volume is increasing at a rate of 10 cubic m/s, then at the moment the radius is 3 m, it is increasing at a rate of

The surface area of the balloon is

and differentiating gives

so that at the moment the radius is 3 m, its area is increasing at a rate of

The anwser is x=20 because you need x alone
The answer is 72 and 3. 72 is x and 3 is y. 72 +3 is 75 and 72 divided by 3 is 24.