Question 1082594
The difficult part here is that the rental cost is an ongoing cost that must be captured over time. So it's $200 every month or week or some time period.
Once you buy the machine, you don't get charged for it every time period.
I'll just work the problem assuming that you only pay a one time rental price.
Machine A: {{{C[A]=200+0.08N}}}
Machine B: {{{C[B]=1200+0.04N}}}
Set them equal to each other.
{{{200+0.08N=1200+0.04N}}}
{{{0.04N=1000}}}
{{{N=1000/0.04}}}
Solve that to get the number of copies.