a. The first variable is x and the second variable is y.
b. The equations are
and 
Step-by-step explanation:
Step 1:
The first step is to define the variables. The variables can be any two symbols, letters, characters, etc.
Here let the first variable be x and the let the second variable be y.
So the variables are defined as x and y.
Step 2:
The sum of the given variables is 12.
The first variable + the second variable = 12,

The difference between the two variables is 4.
The first variable - the second variable = 4.

Step 3:
If we add both the equations we get,
and 
x = 8 and y = 4.
Answer:
PR = 16
SR = 12
Step-by-step explanation:
6/8 = (x-3)/(x+1)
8x-24 = 6x+6
simplify
2x = 30
x = 15
PR = 15 + 1 = 16
SR = 15 - 3 = 12
Answer:
$26.00
Step-by-step explanation:
Using the average daily balance method, the amount to be used in calculating Theresa's interest is given by:

Therefore, the interest charge on Theresa for the biling cycle is given by: