This has already been answered before but...
Part AChorus:Expontential growth = b*a^x b = 15a = 1.12 (a= r+1), r = 12%
Which gives a function of f(x) = 15*1.12^x
BandLinear growth = ax+ba = 2b = 30
Which gives a function of g(x)=2x+30
Part B:f(9) = 15*1.12^9 = 41.59g(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