its word problem

Question

A certain freezing process requires that room temperature be lowered from 40°C at the rate of 5°C every hour . What will be the room temperature 10 hours after the process begins?

Answer 1

Start with T = 40°C, and subtract 5°C every hour.  After t hours,

 

T(t) = 40°C - (5°C/hr)t,

 

where t = hours elapsed since the temperature started falling at a rate of 5°C/hr

 

T(t) = 40 - 5t,

 

with T in °C and t in hours.

 

T(10) = [40 - 5(10)] °C = -10°C