Equivalent equations help you to knock out the choices and solve the problems more easier. for example
x + 6y = 8 2x + 4y = 8 multiply first equation to get rid of from x 2x+12y=16 2x+4y=8 now subtract second equation from first 8y=8 y=1 now put value of y in seond equation 2x+4(1)=8 2x=8-4 2x=4 x=2 hence, equivalent equations help you to solve a system of equations