Please help me 1 2 3 or 4

Icould really use some with this question.

Solve the following pair of equations for x and y: ax/b_ by /a= a +b; ax - by = 2ab

Four equations are shown below.equation 1: y=2*equation 2: y=2x-5equation 3: y=x2 + 6equation 4: tdentify one linear equation and one nonlinear equation from the list.why each equation you identified is linear or nonlinear.nd one nonlinear equation from the list. state a reasonlinear equation