All animals have a pair of front feet. 130 feet is 130÷2 or 65 pairs of feet. There are 40 pairs of front feet. So the remaining 65-40 or 25 pairs of feet are hind feet and belong to the goats, so there are 25 goats and 40-25 or 15 chickens. By algebra, G + C = 40 4G + 2C = 130 Solve that and get G=25 and C=15 Edwin