Farmer Brown has ducks and cows she noticed that there are 32 feet and 12 head how many of the animals are ducks and how many are cow

Call cows C and ducks D4C +2D=32 [for the feet]C + D=12 [for the heads]So from the second C=12-D substitute into the first 4 (12-D)+2D=3248-4D +2D=322D=16 D=8 ducksC=4 cows