Can someone help me in this exercise, it is about functions. Thank you

Answer:
a)
Since the radius of the balloon increases by 5 cm every second, the amount of time passed in seconds multiplied by 5 will give us the radius at any given point in time
So, f(t) = 5t
b)
Since the surface area of a sphere is 4[tex]\pi[/tex] (r)^2
We already have the radius of the sphere at any given time from our first equation
SA(t) = 4[tex]\pi[/tex] (5t)²
Kindly Mark Brainliest, Thanks!