There are 80 monkeys in the park. How many orangutans are there in the park?
①80×( 1+ 3/ 10)
Supplementary conditions: there are three tenths more orangutans than monkeys.
②80÷( 1- 3/ 13)
Supplementary conditions: there are three tenths more monkeys than orangutans.
③80× 13/ 10
Supplementary conditions: monkeys are only 13 times as big as orangutans.
(4) 80- 13%
Orangutans are only 13 times as big as monkeys.