18.50/100 = 0.1850
0.1850 x 20 = 3.70
18.50 - 3.70 = 14.80
14.80/100 = 0.1480
0.1480 x 6 = 0.888
14.80 + 0.88 = 15.68
the final cost would be $15.68
For this case we have a function of the form:

Where,
A: initial amount
b: growth rate (for b> 1)
x: independent variable
y: dependent variable
We then have the following function:

Using the definition, the following statements are correct:
1) The function is exponential
2) The function increases by a factor of 2.5 for each unit increase in x
3) The domain of the function is all real numbers
The slope/y-int form would be y=9/2x+2 you have to move the x value and whole number(y-int) to the other side which would make them negative and then divide by the -2 and there you go.
2/5 + 2/4
8/20 = 10/20
8/20 + 10/20 = 18/20
18/20 = 9/10
9/10 = 0.9
Your answer is 9/10 or 0.9
Hope I helped!
Let me know if you need anything else
~ Zoe
Answer:
9.1
Step-by-step explanation: