Adam has a total of 10 geese and cows.
The difference in their number of legs is 2.
How many (a) cows and (b) geese does Adam have?
Number of
geese |
Number of
geese' legs |
Number of
cows |
Number of
cows' legs |
Difference in the
number of legs |
| 10 |
10 x 2 =
20 |
0 |
0 x 4 =
4 |
20 - 0 =
20 |
| 9 |
9 x 2 =
18 |
1 |
1 x 4 =
4 |
18 - 4 =
14 |
| 7 |
7 x 2 =
14 |
3 |
7 x 4 =
12 |
14 - 12 =
2 |
If all of the animals are geese,
the number of legs needed
= 10 x 2
= 20
Total difference in the number of legs
= 20 - 2
= 18
Difference in the number of legs when 1 goose is replaced by 1 cow
= 20 - 14
= 6
Number of cows
= 18 ÷ 6
= 3 (a)
Number of geese
= 10 - 3
= 7 (b)
Answer(s): (a) 3; (b) 7
