I need help to slove the following: Slove the follwoing system by addition;2x-4y=-7and 4x+2y=9?

Answer 1

2x -4y = -7
4x +2y = 9

Multiply the second equation by 2 and add it to the first
2x - 4y = -7
8x +4y = 18

Now add
10x = 11
Divide both sides by 10
x = 11/10

Now go back to either of the original equations. Replace x with 11/10 and solve for y.
Your answer will be an ordered pair.
2(11/10) - 4y = -7
22/10 - 4y = -70/10
Subtract 22/10 from each side
-4y = -70/10 - 22/10
-4y = -92/10
Divide both sides by -4
y = (-92/10)/(-4)
y = 23/10
Answer: (11/10, 23/10)

Answer 2

2x - 4y = - 7
8x + 4y = 18-----ADD
10x = 11
x = 11 / 10

44/10 + 2y = 9
2y = 90/10 - 44/10
2y = 46/10
y = 23/10

x = 11/10 , y = 23/10