Answer:
x=53
Step-by-step explanation:
pythagoras theorem
a^2 + b^2 =c^2
here a and b are two small sides and c is hypotenuse (longest side)
28^2 + 45^2 = c^2
784 + 2025 =x^2
2809 =x^2
=x
53 =x
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