Finding initial temperature and temperature after 20 min from cooling model

[arroww]

9) A student records the internal temperature of a hot sandwich that has been left to cool on a kitchen counter. The room temperature is 19 degrees Celsius. An equation that models this situation is $$T(t) = 63(0.5)^\frac{t}{10} + 19$$ where $$T$$ is the temperature in degrees Celsius and $$t$$ is the time in minutes.

a) What was the temperature of the sandwich when she began to record its temperature?
b) Determine the temperature of the sandwich after 20 min.I don't really understand what to do..help would be appreciated. Thanks!

 

[MarkFL]

The equation you are given tells you the temperature of the sandwich at time $t$. So, you need to substitute for $t$ and then evaluate the resulting expression on the right side of the equation. What is the value of $t$ for part a)? And for part b)?