Because it is in the middle of those given points
An exponential model can be described by the function

where: a is the initial population or the starting number, b is the base and x is the number of periods elapsed.
When the base of an exponential model is greater than 1 it is called a growth factor, but when it is less than 1 it is called a decay factor.
Given the exponential model

n is the final output of the exponential model, 20.5 is the starting number, 0.6394 is the base and t is the number of periods/time elapsed.
Here, the base is 0.6394 which is less than 1, hence a decay factor.
Therefore, <span>the
base, b, of the exponential model is 0.6394; It is a
decay factor.</span>
(-3,0) and (5, -2)
slope = (0 + 2) /(-3 - 5) = -2/8
y - 0 = -2/8 (x + 3)
y = -2/8 x - 6/8
8y = -2x - 6
2x + 8y = - 6
Answer is
D. 2x + 8y = -6
15% means 0.15 .
'of' means 'times'.
The problem is (0.15) x (63.2) .
I think you can take over and do it from here.