SOLUTION: A farmer has a combined total of 30 pigs and ducks and there is a combined total of 100 legs. How many of each animal is there?

Algebra.Com
Question 730582: A farmer has a combined total of 30 pigs and ducks and there is a combined total of 100 legs.
How many of each animal is there?
Found 2 solutions by Edwin McCravy, lynnlo:
Answer by Edwin McCravy(20060)   (Show Source): You can put this solution on YOUR website!
A farmer has a combined total of 30 pigs and ducks and there is a combined total of 100 legs. How many of each animal is there?
There are two ways to do it -- with algebra and without algebra.  
I'll do both.  

1.  WITHOUT ALGEBRA:
There are 100 legs, so there are 50 pairs of legs. 

Ducks have one pair of legs and pigs have two pairs of leg.

If all 30 were ducks, there would only be 30 pairs of legs.

But there are 50 pairs of legs, so the extra 20 pairs of legs must
belong to the pigs.  

So there are 20 pigs and since there are 30 animals there are 10 ducks.

------------------------------------------------------

2.  WITH ALGEBRA:

 d +  p = 30
2d + 4p = 100


Solve that system by substitution or elimination and get d=10, p=20

Edwin
Answer by lynnlo(4176)   (Show Source): You can put this solution on YOUR website!
TOTAL OF DUCKS AND PIGS=============30
TOTAL LEGS===========100
PIGS============20X4==========80
DUCKS===========10X2==========20
================================
PIGS & DUCKS===30=============100
20=====10
RELATED QUESTIONS

A farmer has 3 types of animals in his barn: chickens, cows and pigs. The farmer has 80... (answered by ikleyn,Edwin McCravy)
farmer frannie has a farm. and onthat arm, she has only ducks and pigs. she is taking... (answered by stanbon)
A Farmhouse shelters 10 animals. some are pigs and some are ducks. Altogether there are (answered by japunzalan13)
a farmhouse shelters 10 animals. some are pigs and some are ducks. altogether there are... (answered by Boreal)
farmer adelita has only ducks and cows. he cant remeber how many of each he has but he... (answered by Edwin McCravy)
Farmer wants to buy cows, pigs and chickens. He has $100 and wants to buy total of 100... (answered by josmiceli,richwmiller)
A group of dogs and ducks have a total of 99 heads and legs among them. There are twice... (answered by stanbon,benazir.sj@gmail.com)
Farmer Bob has a total of 35 cows and chickens on his farm. IF the total number of animal (answered by stanbon)
A farmhouse shelters 10 animals. Some are pigs some are ducks, Altogether there are 36... (answered by ewatrrr,ikleyn)