4
algebra

A stable has horses and rabbits. There are 22 animals with 64 legs. How many horses are there? (Horses have 4 legs, rabbits have 4 legs)

Wait, both have 4 legs, so this won't work. Let me change to horses and chickens.

A stable has horses and chickens. There are 22 animals with 64 legs. How many horses are there? (Horses have 4 legs, chickens have 2 legs)

A

8 horses

B

10 horses

C

12 horses

D

14 horses

Correct Answer: B

Choice B is the correct answer. Let hh = horses and cc = chickens.

System: {h+c=224h+2c=64\begin{cases} h + c = 22 \\ 4h + 2c = 64 \end{cases}

Step 1: From first: c=22hc = 22 - h

Step 2: Substitute: 4h+2(22h)=644h + 2(22 - h) = 644h+442h=644h + 44 - 2h = 642h=202h = 20h=10h = 10

Solution: 10 horses (and 12 chickens)

Verification: 10+12=2210 + 12 = 22 ✓ and 4(10)+2(12)=40+24=644(10) + 2(12) = 40 + 24 = 64

💡 Strategic Tip: Different leg counts create solvable systems.

**Other choices fail verification.