Question 273368
4s+2c=56
s+c=21 or s=21-c
4(21-c)+2c=56
84-4c+2c=56
-2c=56-84
-2c=-28
c=-28/-2
c=14 chickens.
s=21-14=7 sheep.
Proof:
4*7+2*14=56
28+28=56
56=56