answer C
to eliminate x, multiply the top equation by 7 then add the equations
it is not A because if the bottom equation is multiplied by 6, the y’s will not cancel out if the bottom is subtracted from the top (since 6x - -6x is 12 not 0)
it is not B because adding the equations will not eliminate either variable
doing option C eliminates x since -7x + 7x is 0