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: The answer is (b) making sure she has a positive credit history.
Step-by-step explanation: Given that Yolo is buying a car from a local car dealership and wants to get the lowest interest rate possible. We are to select the correct option which will most likely help her.
From the given options, we can see that she will get the lowest interest rate possible if she has a positive credit score.
Thus, (b) is the correct option.
360/60 = 6
6 degrees every second
6*20 = 120 degrees
120 degrees after 20 seconds
6 * 45 = 270
270 degrees after 45 seconds
Hope I helped!
Let me know if you need anything else!
~ Zoe
35,000 cm = .35 km
is your answer