Posted by **Anonymous** on Thursday, March 7, 2013 at 7:10am.

A farm rears 9 ducks and cows in his farm. There are 28 legs altogether.How many ducks are there in the farm?

- Maths -
**Dr. Jane**, Thursday, March 7, 2013 at 10:24am
d + c = 9

2d + 4c = 28

Multiply the top equation by -2 and add. This will give you the number of cows. Find the ducks by substituting into the first equation.

- Maths -
**nanayeboahford**, Thursday, March 7, 2013 at 1:33pm
let d=number of ducks reared

c=number of cows reared

sum of ducks and cows=d+c=9

sum of their legs=2d+4c=28 since duck has two legs and cow also has 4 legs

the two equations give

d+c=9...1

2d+4c=28...2

multiply eqn 1 by 2

2(d+c=9) which gives 4d+4c=18..3

now 2d+4c=28

-2d+2c=18

we have 2c=10

therefore c=5 put c into eqn..1

to get d+5=9

d=4 meaning there are 4 ducks and 5 cows.proof2*4=8legs in all does 4 ducks and 4*5=20 legs in all does 5 cows.

## Answer This Question

## Related Questions

- Maths - A farm rears 9 ducks and cows in his farm. There are 28 legs altogether....
- maths - the total number of cows and ducks on a farm is 35.All the cows have 74 ...
- maths - the total number of cows and ducks on a farm is 35.All the cows have 74 ...
- maths - There are a total of 50 ducks and goats in a farm. They have 154 legs ...
- Math - Mr McDonald has some ducks and goats in his farm. If he counted a total ...
- Math - There are 42 goats and chickens in the farm.there are 114 legs altogether...
- Math - How many line segments can be drawn between each 15 points? No three ...
- math - A farm has cows and ducks. There are 78 feet and 27 hands. How many of ...
- Math - Mohammed had ducks and cows on his farm. These 14 animals had a total of ...
- Math - Old McDonald has cows and chickens on his farm. If the animals on his ...

More Related Questions