SOLUTION: Lydia and Nazeerah were walking to school when they spotted a herd of 30 cows and
ducks on a farm. If there were a total of 92 animal legs, calculate the number of
cows and the n
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ducks on a farm. If there were a total of 92 animal legs, calculate the number of
cows and the n
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Question 1185605: Lydia and Nazeerah were walking to school when they spotted a herd of 30 cows and
ducks on a farm. If there were a total of 92 animal legs, calculate the number of
cows and the number of ducks on the farm. Found 2 solutions by Plocharczyk, Edwin McCravy:Answer by Plocharczyk(17) (Show Source):
You can put this solution on YOUR website! Question 1185605
Lydia and Nazeerah were walking to school when they spotted a herd of 30 cows
and ducks on a farm. If there were a total of 92 animal legs, calculate the
number of cows and the number of ducks on the farm.
The easy way requires no algebra, just basic arithmetic.
If the 30 animals had all been ducks, there would have been only 60 legs. The
extra 32 legs were pairs of hind legs belonging to 16 cows. So there were 16
cows and 30-16 or 14 ducks.
But your teacher probably won't accept that easy way and expects you to use
algebra.
Let c = the number of cows
Let d = the number of ducks
Then
the number of legs on the cows = 4c
the number of legs on the ducks = 2d
So the system is
Multiply the first equation by -2 to eliminate d
and add the equations term-by-term:
-2c-2d = -60
4c+2d = 92
------------
2c = 32
c = 16 <-- so there were 16 cows.
Substitute in c+d = 30
c+d = 30
16+d = 30
d = 14 <-- so there were 14 ducks.
Edwin
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