Answer:
Given an exponential function of the form
y = a*(b)^x
The values of b that will result in the desired percentage values are:
Case 1
b = 23% decrease
1 - 0.23 = 0.77
y = a*(0.77)^x
Case 2
b = 8% increase
1 + 0.08 = 1.08
y = a*(1.08)^x
Case 3
b = 15% decrease
1 - 0.15= 0.85
y = a*(0.85)^x
Case 4
b = 120% increase
1 + 1.2 = 2.2
y = a*(2.2)^x
See attached picture for examples
