Bob keeps his cows and ducks in a barn. There are 13 animals in the barn and all together they have 34 legs. How many cows are there and how many ducks

4 cows and 9 ducks

Step-by-step explanation:

X is cows and Y is ducks

X+Y = 13

4*X + 2*Y = 34

- X+Y = 13

-4*X + 2*Y = 34

4*X + 2*Y = 34

2*X + 2*Y = 26

2*X = 8

X = 4

X+Y = 13

Y = 13-4

Y=9