How many hectares is 21.6 square kilometers

How many hectares is 21.6 square kilometers

2160 ha

5 square kilometers = () hectares = () square meters

5 square kilometers = (500) hectares = (5000000) square meters

3.4 square kilometers = () hectares = () square meters
There is another project. Party a works alone for two fifths of an hour, Party B works alone for two thirds of an hour, and Party A works together for several hours?

3.4 square kilometers = 340 hectares = 3400000 square meters
Assuming that the quantity of work is 1 and there are 10 copies, Party A needs 2 / 5 ／ 10 time, and Party B needs 2 / 3 ／ 10 time
1÷(1/25+1/15)