To successfully use this if a variable is not by itself then you must make sure the coefficients are the same and the signs are different, if they are the same you must multiply by -1, -2 or their positive equivalents, then with the remaining x you divide it to both sides of the equation, this will be your X. Finally you must substitute your new X for the X in the original version in one of the two equations, then subtract the actual number to both sides and divide, the remainder is your Y.