Pakai cara yahh no. 22

Volume
= 18m³ = 18.000 Liter

Debit selang
= 90Liter/menit + 60Liter/menit
= 150 Liter/menit

Waktu
= Volume : Debit
= 18.000 Liter :150L/menit
= 120 Menit