Adam has a total of 11 chickens and donkeys.
The difference in their number of legs is 10.
How many (a) donkeys and (b) chickens does Adam have?
Number of chickens |
Number of chickens' legs |
Number of donkeys |
Number of donkeys' legs |
Difference in the number of legs |
11 |
11 x 2 = 22 |
0 |
0 x 4 = 4 |
22 - 0 = 22 |
10 |
10 x 2 = 20 |
1 |
1 x 4 = 4 |
20 - 4 = 16 |
9 |
9 x 2 = 18 |
2 |
9 x 4 = 8 |
18 - 8 = 10 |
If all of the animals are chickens,
the number of legs needed
= 11 x 2
= 22
Total difference in the number of legs
= 22 - 10
= 12
Difference in the number of legs when 1 chicken is replaced by 1 donkey
= 22 - 16
= 6
Number of donkeys
= 12 ÷ 6
= 2 (a)
Number of chickens
= 11 - 2
= 9 (b)
Answer(s): (a) 2; (b) 9