It should be A if I did the math right which I think I did
The first thing you do is subtract 2 from both sides to move the 2 to the left side
3-6x=7x
now add 6x to both sides to move -6x to the right
3=13x
divide by 13 to eliminate the 13 on the right side
3/13
2x-y=7
y=2x+3
Substitute (2x+3) in for y in the first equation
2x-(2x+3)=7
2x-2x-3=7
-3=7
Becuase -3 does not equal 7 the answer is no solution