How to solve the problem of chickens and rabbits in the same cage

High-quality solution

With X chickens, there are (35-X) rabbits

2X+4(35-X)=94

140-2X=94

2X=46

X=23

Then there are 35-23=12 rabbits

There's another idea which is even easier

This is to say, all the animals can understand human speech. p>Assuming that all chickens and rabbits understand human speech

First, all animals listen to the command: lift one foot! All the animals lift one foot

And then, all the animals listen to the command: Lift one foot again! All the animals lift one foot again

Then the number of feet left on the ground is 94-35-35=24 feet

Then all the chickens sit down on the ground, but each rabbit has 2 feet left on the ground

So the remaining 24 feet are rabbits' feet, and the number of rabbits is 24 ÷ 2=12

The chickens are 35 - 12=23

The animals lift one foot again

And then, all the animals listen well to the command: lift one foot again! 12=23