Find the lowest common denominator of either x or y. x in this example. ( 12x )Multiply both equations such that the x's match this. ( 1) 12x + 8y = 16 & 2) 12x + 15y = 51 )Combine these formulas by taking one from the other. ( 7y = 35 )Solve for y. ( y = 5 )Put y back in to find x. ( x = -2 )Put both x and y in to confirm ( (4*-2) + (5*5) = 17 )