It says to use the addition method, but I don't know what that is.
the point is probably to help you solve it, so if you can dof it another way, that would work as well as long as you get the right answer
but this is the addition method:
1st: Line up the variables in both equation, x above x, y above y, = above =, constant above constant. 2nd: (Optional) Multiply one or both equations so the coefficients of one variable are opposites. 3rd: Add the equations to eliminate one variable. 4th: Solve.