How do you simplify (7 + 6w)6 what are the steps

Just distribute the 6 into the terms inside the brackets.
42+36w

Part A
Chorus:
Expontential growth = b*a^x 
b = 15
a = 1.12              (a= r+1), r = 12%

Which gives a function of f(x) = 15*1.12^x 

Band
Linear growth = ax+b
a = 2
b = 30

Which gives a function of g(x)=2x+30

Part B:
f(9) = 15*1.12^9 = 41.59
g(9) = 2*9+30 = 48

Part C:
This is probably problem solving, where you're allowed to use calculators and other softwares.

Therefore you can use different softwares, and make f(x) = g(x).
I did this, and got it to 10.95427141