3math problem show step by step


1. 5x+y=-12
5x-7y=4

2. -5x+4y=-3
-9x-y=-30

3, -9x+6y=27
-x+3y=10

Number 1
- Multiply the first one by negative one so the x’s are opposites. (-5x-y=12)
- Simplify them
-5x-y=12
5x-7y=4
-8y=16
y=-2
-Fill in y to one of them to find x (x=-2)

Number 2
-Multiply the bottom one by 4 so it is opposite to the first one (-36x-4y=-120)
-Simplify
-5x+4y=-3
-36x-4y=-120
-41x=-123
x=3
-Fill x into one of the problems to find y (y=3)

Number 3
-Multiply the bottom one by -2 to make it opposite (2x-6y=-20)
-Simplify
-9x+6y=27
2x-6y=-20
-7x=7
x=-1
-Fill into one of the equations to get y (y=3)