Answer:
Temperature drops to -10 deg C after 5.5 minutes and remains at that temperature.
Step-by-step explanation:
[tex]t_{1} = 1, T_{1} = 80\\\\t_{2} = 2, T_{1} = 60\\\\t_{3} = 3, T_{3} = 40\\\\t_{4} = 4, T_{4} = 20\\\\t_{5} = 5, T_{5} = 0\\\\t_{6} = 6, T_{6} = -10\\\\t_{7} = 7, T_{7} = -10\\\\t_{8} = 8, T_{8} = -10\\\\t_{9} = 9, T_{9} = -10\\\\t_{10} = 10, T_{10} = -10\\[/tex]