Whats the answer to this
24 April 2005, 10:46 PM
#1
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Whats the answer to this
a farmer keeps cows and chickens if there are 81 heads and 252 legs how many cows and chickens are there
please give me the answer and how to work it out
please give me the answer and how to work it out
24 April 2005, 10:55 PM
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let x be number of cows and y be number of chickens
we know that
xCows +yChickens = 81 (1)
and
4xCows + 2yChickens = 252 (2) (ie cows have 4 legs, chickens 2 and the total is 252 legs)
from equ 1 multiply both sides by 2 gives
2xCows + 2yChickens = 162 (3)
subtract equ (3) from equ (2) gives 2xCows = 90 therefore x = 45, substitute in and get y
Hope that helps!
we know that
xCows +yChickens = 81 (1)
and
4xCows + 2yChickens = 252 (2) (ie cows have 4 legs, chickens 2 and the total is 252 legs)
from equ 1 multiply both sides by 2 gives
2xCows + 2yChickens = 162 (3)
subtract equ (3) from equ (2) gives 2xCows = 90 therefore x = 45, substitute in and get y
Hope that helps!
24 April 2005, 11:03 PM
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Cheers 
that question was set for my 11 year old son at junior school as part of his homework and i have been sat for 10 mins tryin to work it out lol 
that question was set for my 11 year old son at junior school as part of his homework and i have been sat for 10 mins tryin to work it out lol
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