In piscina curg printr-un robinet 21dal/30min, adica 420l/ora
Prin 3 robinete curg 3x420=1260l/ora
In total curg 9x1260 l=11340l
Din piscina curg prin alt robinet 315l/30min adica 630l/ora, in 9 ore curg 9x630l=5670l
Dupa 9 ore vor fi in piscina 11340-5670=5670l