Jill's fish weighs 8 times as much as her parakeet. Together they weight 63 ounces. How much does the fish weight

F=8p

63=f+p

Use substitution. f is already isolated, so sub the equation 8p into 63=f+p for f.

63=8p+p

63=9p

Divide both sides by 9 to get

p=7

You now have the weight of the parakeet. Multiply 7 by 8 to get the weight of the fish.

f=56