Final answer:
Using a system of equations based on the number of heads and legs, we determine that the farm has 27 hens, represented by option D.
Step-by-step explanation:
The question asks us to determine the number of hens on a farm when there are a total of 84 heads and 282 legs visible. We can set up a system of equations to solve this problem since hens have 2 legs and pigs have 4 legs. If we let H represent hens and P represent pigs, we can write two equations based on the heads and legs:
- H + P = 84 (each animal has one head)
- 2H + 4P = 282 (each hen has 2 legs and each pig has 4 legs)
To solve for the number of hens, we can multiply the first equation by 2 and subtract it from the second equation to eliminate P from the equations:
2H + 2P = 168 (multiplying the first equation by 2)
Now subtract this from the second equation:
2H + 4P - (2H + 2P) = 282 - 168
2P = 114
P = 57
Now that we know there are 57 pigs, we can substitute back into the first equation to find the number of hens (H):
H = 84 - P
H = 84 - 57
H = 27
Therefore, there are 27 hens on the farm, which corresponds to option D.