the air in a room with volume 180 m3 contains 0.1% carbon dioxide

The air in a room with volume 180 m³ contains 0.1% carbon dioxide initially. Fresher air with only 0.05% carbon dioxide flows into the room at a rate of 2 m³/min and the mixed air flows out at the same rate.

Find the percentage of carbon dioxide in the room as a function of time t (in minutes).
p(t) = 

1

What happens with the percentage of carbon dioxide in the room in the long run? 

lim t → ∞ p(t) = 2[removed]  %