Adam has a total of 12 geese and donkeys.
The difference in their number of legs is 6.
How many (a) donkeys and (b) geese does Adam have?
Number of geese |
Number of geese' legs |
Number of donkeys |
Number of donkeys' legs |
Difference in the number of legs |
12 |
12 x 2 = 24 |
0 |
0 x 4 = 4 |
24 - 0 = 24 |
11 |
11 x 2 = 22 |
1 |
1 x 4 = 4 |
22 - 4 = 18 |
9 |
9 x 2 = 18 |
3 |
9 x 4 = 12 |
18 - 12 = 6 |
If all of the animals are geese,
the number of legs needed
= 12 x 2
= 24
Total difference in the number of legs
= 24 - 6
= 18
Difference in the number of legs when 1 goose is replaced by 1 donkey
= 24 - 18
= 6
Number of donkeys
= 18 ÷ 6
= 3 (a)
Number of geese
= 12 - 3
= 9 (b)
Answer(s): (a) 3; (b) 9