posted by ANITA .
PIGS HAVE 4 LEGS - CHICKENS HAVE 2 EACH ... IF YOU HAVE A TOTAL OF 50 LEGS ON 18 TOTAL ANIMALS HOW MANY CHICKENS AND HOW MANY ARE PIGS?
Let C=number of chickens and P=number of pigs
2. P=18-C (isolate a variable)
3. 2C+4P=50 (Each chicken has two legs, each pig has four legs, and adds up to 50 legs).
4. 2C+4(18-C)=50) Substitute 18-C for P because step 2 shows P=18-C.