2x + 7y =  1     (1)
2x - 4y = 12     (2)

Distract (2) from (1) (both sides). You will get

7y - (-4y) = 12 - 1,

11y = -11.

What is your next step?

From this point please complete the solution yourself.

2x + 7y = 1 -------- eq (i)

2x - 4y = 12 ------- eq (ii)

First thing to do is: Subtract eq (ii) from eq (i)

Doing so, you should get:  

RELATED QUESTIONS

Solve the system of linear equations using the Gauss-Jordan elimination method.
x	 + 	y	  (answered by richwmiller)

Solve the system of linear equations using the Gauss-Jordan elimination method.
2x	 +... (answered by richwmiller)

Solve the following system of linear equations by the elimination method:
y=2x-5... (answered by uma)

Solve the system of linear equations using the Gauss-Jordan elimination method.
3x	 +... (answered by solver91311)

Solve the system of linear equations using the Elimination Method.
x+4y=6... (answered by mananth)

Solve the system using elimination.
 
2x − y + 3z = −2 [1]
−x + 2y... (answered by Boreal)

Solve the system of linear equations 2x-5y=16 and 4x+3y=6 by using... (answered by mananth)

I'm having alot of trouble understanding the process of solving a system of equations by... (answered by stanbon,THABANIG@YMAIL.COM)

Solve the system of equations by the method of elimination. 

x-4y=-7... (answered by Jk22)