EQUATION 1: x-y=12
EQUATION 2: 3x+y=4
STEP 1:
solve for one variable in equation 1
x - y= 12
add y to both sides
x= 12 + y
STEP 2:
use x value from step 1 and substitute in equation 2
3x + y= 4
3(12 + y) + y= 4
multiply 3 by parentheses
(3*12) + (3*y) + y= 4
multiply inside parentheses
36 + 3y + y= 4
combine like terms
36 + 4y= 4
subtract 36 from both sides
4y= -32
divide both sides by 4
y= -8
STEP 3:
substitute y value from step 2 into either equation
x - y= 12
x - (-8)= 12
x + 8= 12
subtract 8 from both sides
x= 4
CHECK:
x= 4, y= -8
3x + y= 4
3(4) + (-8)= 4
12 - 8= 4
4= 4
ANSWER: The x value is 4 and the y value is -8.
Hope this helps! :)