Kalkulesen bilong hamas win i go insait long 'ventilation system'
F - Seip bilong kros-seksen bilong 'air duct'. Rektangular o raunpela.
D - Diamita bilong 'duct'.
X - Bikpela bilong 'rectangular duct'.
Y - Hait bilong wanpela 'rectangular duct'.
E - Spit bilong win, long wan wan seken.
Ol samting bilong program.
Kalkulesen bilong volium bilong win i go insait long 'ventilation duct'.