To solve this problem we will use the following formula for compounded interest:

where A₀ is the initial amount, r is the interest rate as a decimal number, and t is the number of years.
Substituting A₀=800, r=0.7, and t=5 we get:

Simplifying the above result we get:

Answer:
In five years, you should be earning about $11360 per month, because your earnings rise 70% per year, which are added to the earnings of the previous month.