There are 1000 rabbits and chickens on a farm, and together they have 3150 legs. How many rabbits and how many chickens are there on the farm?

Answer 1

number of rabbits ---- r
number of chickens = 1000 - r

rabbits have 4 legs, and chickens have 2 legs, so
4r + 2(1000 - r) = 3150

solve for r, and you have the number of rabbits,
chicken number is 1000 - the r value you found