Expression A: S= 100+ 100(0.15y) y=Commission
Expression B: S= 150+ 150(0.10y)
Now to get Part B done. Plug in numbers for Y and use the results as the sales continue to increases. For example, start with 5 sales, then go to 10 then 15, and so on and so fourth. Hope I was able help you understand the question a little bit more! :)
Assuming he had not dealt with the bank offering plan B before, he has nothing deposited two years back. Hence plan B only gives him only 0.2% annual interest for his deposit.
Plan A gives 0.25% for his deposit all the time.
So plan A is more advantageous.
For durations,
To reach $1,000,000 from $100,000, the money needs to grow 10 fold, or
(1+i)^n=10
n=log(10)/log(1+i).
So for plan A:
n=log(10)/log(1.0025)=922.18 years, while for
plan B
n=log(10)/log(1.0020)=1152.44 years.
Hope the bank(s) still exist at that time.
