Which is the best first step and explanation for solving this system of equations?

Answer:   see belowStep-by-step explanation:Since 2x appears on the left side of both equations, that term can be eliminated by subtraction, which is what the first choice suggests.The result will be ...   3y = 7 -4y +5 . . . . . . . . . second equation subtracted from the first   7y = 12 . . . . . . add 4y   y = 12/7 . . . . . . divide by 7__However, the fact that 2x is by itself on the left side of the second equation suggest that substitution may also be a good option. Perhaps an equally good first step is to use the expression in the second equation to substitute for 2x in the first:   (4y -5) +3y = 7Either way, the resulting equation is 2-step.   7y = 12 . . . add 5   y = 12/7 . . . divide by 7___The other suggested "first steps" do nothing useful.