The surface area S (-) (in square meters) of a spherical balloon with radius r meters is given by S(r) = 4xr?. The radius P (1) (in meters) after t seconds is given by P (t) = .
Write a formula for the surface area N (t) (in square meters) of the balloon after t seconds.
It is not necessary to simplify.

n=9

step-by-step explanation:

7 times a number = 7n

decreased by 13 = 7n-13

same as is =

5 times the number = 5n

increased by 5 = 5n+5

7n-13 = 5n+5

2n=18

n=9

answer: 8 years

step-by-step explanation:

the explanation is that in 8 years the child will be 20 and in 8 years the father will be 40 and 20 is half of 40.

if i did my math right then the answer should but 108