Question

Solve using addition method.
2x-y=7
x+2y=1

Answer 1

Multiply the first eqn by 2 throughout and add the two eqn to eliminate the y term

Answer 2

2x-y=7
therefore 4x-2y=14....(1)
x+2y=1.....(2)
add 1 and 2 you will get 5x=15 as 2y will be canceled out.
so x=3.
putting x in eqn 2 you will get 2y=-4=> y=-2.

Answer 3

4x -2y = 7
x + 2y = 1

Adding both
5x = 8
So x = 8/5

Answer 4

Sorry, it is

4x -2y = 14
x + 2y = 1

Adding both
5x = 15
So x = 15/5 ie 3

Answer 5

Then as dipankar has done