For elimination, you need to eliminate one of the variables by subtrating the two equations. To do that, you need to multiply the equation 3x+y=17 by 2, which becomes 6x + 2y = 34.
Now you can subtract, but also multiply 6x+2y=34 by -1 so you can subtract: 4x + 2y = 20 -6x - 2y = -34 ----------------- -2x + 0 = -14 x = 7
Now that you know x=7, plug it back in to one of the original equations to solve for y. 4x + 2y = 20 4(7) + 2y = 20 28 + 2y = 20 2y = -8 y = -4
