Let X be chickens Let Y be pigs, then x+y=13 the animals have 2x+4y legs, so 2x+4y=40 The system of the equations [X+y=13 [2x+4y=40 Divide the second equation by 2 [x+y=13 [x+2y=20 subtract the first equation from the second one y=20-13 y-7 pigs substitute y=7 into the first equation x+7=13 x=13-7 x=6 chickens
