fish + parrot = 63 ounces
The task can be formulated differently. Weight is one fish and one parrot . We take fish scales . Instead of fish we put eight parrots. Weight will not change. So nine parrots weighs 63 ounces . One parrot is 1/9 , and one fish is 1 - 1/9 = 9/9 - 1/9 = 8/9
1/9 + 8/9 = 100% 63 ounces
63 ounces * 1/9 = 7 ounces parrot
63 ounces * 8/9 = 56 ounces fish
