Space shuttle problem, If an astronaut exhales 19 L of air a minute... ?

The space shuttle environmental control system handles excess CO2 (which the astronauts breathe out; it is 4.0% by m of exhaled air) by reacting it with lithium hydroxide (LiOH) pellets to form lithium carbonate (Li2CO3) and water. If there are 5 astronauts on board the shuttle, and each exhales 19 L of air per minute, how long could clean air be generated if there were 24,997 g of LiOH pellets available for each shuttle mission? ume the density of air is 0.0010 g/mL.