No 18, 19, 20, 21 jawab dong please

No18.56liter/menit×8 menit=448liter×1 dmkubik=448 dm kubik
No19. 720 liter:2 liter/detik:60 detik=6 menit
No20.1,5 liter/menit×2 menit=3 liter×15 orang=45 liter
No21.18.000mkubik:200m/menit:60 menit=1,5 jam