The temperature of a cooling liquid over time can be modelle

The temperature of a cooling liquid over time can be modelled by exponential function T(x)=60(1/2)^x/30+20, where T is the temperature, in degrees Celsius, and x is the elapsed time, in minutes.
Graph the function
Determine how long it takes for the temperature to reach 28°C

Solution

T(x)=60(1/2)^x/30+20

28=60(1/2)^x/30+20

8=60(1/2)^x/30

8/60=(1/2)^x/30

log(4/15)=(x/30)log(1/2)

log(4/15)/log(1/2)=x/30

1.90689=x/30

x=57.2minutes