Question

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

Answer 1

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