There are some donkeys, hens and cows in a farm.There are 4 times as many hens as cows. Shannon finds out that among the animals, there are a total of 31 heads and 84 legs. How many donkeys are there?
Number of
4-legged animals |
Total legs of
4-legged animals |
Number of
2-legged animals |
Total legs of
2-legged animals |
Total legs |
31
|
31 x 4 =
124 |
0
|
0
|
124
|
30
|
30 x 4 =
120 |
1
|
1 x 2 =
2 |
122
|
11
|
11 x 4 =
44 |
20
|
20 x 2 =
40 |
40 |
Total number of legs if all are 4-legged animals
= 4 x 31
= 124
Big difference between all the 2-legged animals and all the 4-legged animals
= 124 - 84
= 40
Small difference between one 2-legged animal and one 4-legged animal
= 4 - 2
= 2
Number of hens
= 40 ÷ 2
= 20
Number of 4-legged animals
= 31 - 20
= 11
Number of cows = 1 u
Number of hens = 4 u
4 u = 20
1 u = 20 ÷ 4 = 5
Number of cows
= 1 u
= 5
Number of donkeys
= 11 - 5
= 6
Answer(s): 6
