math
posted by jamie .
A farm has cows and ducks. There are 78 feet and 27 hands. How many of each animal are there? How do you know?

Hands? Is this a trick question?
Hmmm. Surely you know ducks don't have hands, nor cows. Wondering if your teacher knows.
I will assume heads.
leg equation: 4C+2D=78
head equation: C+D=27
This assumes of course, no two headed cows are ducks.
so solve the two equations for C and D.
Hint> multiply the second equation by 2, and then subtract the second equation from the first. 
Yhrhg