Answer:
1. x = -12+y / 5 , y = -12-5x
2. x = 4 - y , y = 4 - x
3. x = -11 - 9y / 6 , y = 11 + 6x / 9
( for the numbers in fractions such as the x value for #1 and x & y value for #3, put the negative sign in front of the fraction, not the number okay? )
Explanation:
---> -5x - y = 12 -5x - y = 12
= -5x - y = 12 = +5x +5x
+y +y ---------------------
--------------------- -y = 12 + 5x
-5x = 12 + y /-1 /-1
/-5 /-5 ----------------------
--------------------- y = -12-5x
x = -12+y / 5
-------------------------------------------------------------------------------------------
---> x + y = 4 x + y = 4
= -y -y = -x -x
--------------------- ----------------
x = 4 - y y = 4 - x
--------------------------------------------------------------------------------------------
-----> -6x + 9y = 11 -6x + 9y = 11
= -9y -9y = +6x +6x
------------------------------ ------------------------
-6x = 11 - 9y 9y = 11 + 6x
/-6 /-6 /9 /9
------------------------------- --------------------------
x = -11 - 9y / 6 y = 11 + 6x / 9