2x+4×(24-x)=56

2x+4×24-4x=56

2x+96-4x=56

2x=40

x=20

24-x=24-20=4 (only)

A: There are 20 chickens and 4 rabbits.

Or if there are x rabbits, there are 24-x chickens.

4x+2×(24-x)=56

4x+2×24-2x=56

4x+48-2x=56

2x=8

x=4

24-x=24-4=20 (only)

A: There are 20 chickens and 4 rabbits.

Arithmetic method: suppose that all 24 chickens are chickens.

56-24×2=8 (strips) 8÷(4-2)=4 (only) 24-4=20 (only)

Or suppose that all 24 rabbits are rabbits.

24×4-56=40 (strips) 40(4-2)= 20 (only) 24-20=4 (only)

A: There are 20 chickens and 4 rabbits.