Check the attachment for answer.
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:
sorrie
Step-by-step explanation:
no answer here :)
Answer:
x=13
Step-by-step explanation:
ok so let x+y=22
--------------------------------------------------------
x and y are the 2 unkown Number
-------------------------------------------
x-y=4
their difference is 4
----------------------------------
add both equations
(x+y=22)
+(x-y=4)
------------------------------
y's cancel out
-----------------------
2x=26
-----------------
x=13
Answer:
6
Step-by-step explanation:
if you do the ratio 9/12 and 3/x and cross multiply, x=6... I believe
Because