Question 263824
Say the number of goats is G, then the number of chickens is 40 - G as there are 40 heads and each chicken and each goat has one head.
The number of feet is 130 
So 2(40 - G) + 4G = 130
So 80 - 2G + 4G  = 130
2G = 50
G = 25
25 goats  and 15 chickens