4x=y+47, we can subtract 47 from both sides to get: 4x-47=y, now we know what y equals in terms of x, so we can substitute that in to the other equation: 2x+3y=55 becomes 2x+3*(4x-47)=55 which becomes: 2x+12x-141=55 which becomes 14x-141=55 and we can add 141 to both sides: 14x=196, divide 14 by both sides, we get x=14, which we can substitute back into the y=equation: 4x-47=y becomes 14*4-47=y which becomes y=9 x=14, y=9 x-y=14-9=5
