Question

Given the system of linear equations.

\left \{ {{x+y=7} \atop {2x+y=5}} \right.
Choose all of the options that could be used to solve the system using addition

Multiply the first equation by -1 and add the equations together.
Multiply the second equation by -1 and the first equation by -1, then add the equations together.
Multiply the second equation by -1 and add the equations together.
Multiply the first equation by -2 and add the equations together.
Multiply the first equation by 2 and the second equation by -1, then add the equations together.

Answer 1

x + y = 7
2x + y = 5

multiply 1st equation by -1, then add equations --- this is correct
multiply 2nd equation by -1, then add equations -- this is correct
multiply 1st equation by -2, then add equations -- this is correct
multiply 1st equation by 2 and 2nd equation by -1, then add -- correct

It appears all but 1 of the answer choices will work