Answer:
(1) For x = –12, g (x) = -9
For x = –9, g (x) = -3
For x = –6, g (x) = 3
For x = –3, g (x) = 9
(2) The principal amount of money is $80.
Explanation:
(1)
The expression of g (x) is,

The complete table is:
x g (x)
-15

-12

-9

-6

-3

0

(2)
The formula for simple interest is:

Given:
I = $40
r = 10%
t = 5 years.
Compute the value of P as follows:



Thus, the principal amount of money is $80.