There would be a 0.71% decrease, rounded to the nearest tenth of a percent would be a 0.7% decrease. :)
For this case, the first thing we must do is define variables.
We have then:
x: number of minutes
y: final temperature
We write then the equation that models the problem:

For y = 20 we have:

Clearing x:
Answer:
The temperature of the water will be 20 degree celcius after 150 minutes
Answer: X = -9
Step-by-step explanation:
You can set up a ratio to solve this.
208/13 = -144/x
208x=-1872
x = -9