Answer:
The required equation is .
Step-by-step explanation:
Consider the provided information.
The Initial value of poster = $ 18
After 1 year amount of increase = $ 20.70
With the rate of 15% = 0.15
Let future value is y and the number of years be x.
Now verify this by substituting x=1 in above equation.
Which is true.
Hence, the required equation is .