The volume of a sphere ishi i had two questions first one

A spherical balloon is being filled with helium at a rate of 8cm^3/s at what rate is the radius increasing when the radius is 12cm

Differentiate:

Plug in your knowns and solve for dr/dt. dV/dt=8 and r=12.

When it has been filling for 33.5 seconds, its volume is 268 cm^3. 8(33.5)=268

Therefore, at that time its radius is

Solve for r and plug all the info into the dV/dt formula and solve for dr/dt