Adam has a total of 13 chickens and donkeys.
The difference in their number of legs is 2.
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 |
13 |
13 x 2 = 26 |
0 |
0 x 4 = 4 |
26 - 0 = 26 |
12 |
12 x 2 = 24 |
1 |
1 x 4 = 4 |
24 - 4 = 20 |
9 |
9 x 2 = 18 |
4 |
9 x 4 = 16 |
18 - 16 = 2 |
If all of the animals are chickens,
the number of legs needed
= 13 x 2
= 26
Total difference in the number of legs
= 26 - 2
= 24
Difference in the number of legs when 1 chicken is replaced by 1 donkey
= 26 - 20
= 6
Number of donkeys
= 24 ÷ 6
= 4 (a)
Number of chickens
= 13 - 4
= 9 (b)
Answer(s): (a) 4; (b) 9