You have eight animals that have a total of 20 legs between them. Some are chickens and some are rabbits. How many are chickens and how many are rabbits?
🐇 🐇 🐇 🐇 🐇 [5]
🐇 🐇 🐇 🐇 🐤 🐤 [6]
🐇 🐇 🐇 🐤 🐤 🐤 🐤 [7]
🐇 🐇 🐤 🐤 🐤 🐤 🐤 🐤 [8]
🐇 🐤 🐤 🐤 🐤 🐤 🐤 🐤 🐤 [9]
🐤 🐤 🐤 🐤 🐤 🐤 🐤 🐤 🐤 🐤 [10]
| Rabbits | Chickens | Calculation | Legs |
|---|---|---|---|
| 8 | 0 | 8x4 + 0x2 | 32 |
| 7 | 1 | 7x4 + 1x2 | 30 |
| 6 | 2 | 6x4 + 2x2 | 28 |
| 5 | 3 | 5x4 + 3x2 | 26 |
| 4 | 4 | 4x4 + 4x2 | 24 |
| 3 | 5 | 3x4 + 5x2 | 22 |
| 2 | 6 | 2x4 + 6x2 | 20 |
| 1 | 7 | 1x4 + 7x2 | 18 |
| 0 | 8 | 0x4 + 8x2 | 16 |
4R + 2C = 20 (1)
R + C = 8 (2)
Divide (1) by 2
2R + C = 10 (3)
R + C = 8 (2)
Subtract (2) from (3)
R = 2
Substitute 2 for R in (2)
2 + C = 8
Subtract 2 from both sides
C = 6