Given the system of linear equations. choose all of the options that could be used to solve the system using addition x + y = 7 2x + y = 5 (could be more than one answer) 1.multiply the first equation by -1 and add the equations together. 2.multiply the second equation by -1 and the first equation by -1, then add the equations together. 3.multiply the second equation by -1 and add the equations together. 4.multiply the first equation by -2 and add the equations together. 5.multiply the first equation by 2 and the second equation by -1, then add the equations together.