X would =18 because 18+2= 20
20 x .5 = 10
X = 18
I am not sure, but I checked my answer and I am right. Hope this helps, thank you :) !!
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:
4 meters
Step-by-step explanation:
Given a quadratic equation in which the coefficient of
is negative, the parabola opens up and has a maximum point. This maximum point occurs at the line of symmetry.
Since the divers height, y is modeled by the equation

Step 1: Determine the equation of symmetry
In the equation above, a=-1, b=2, c=3
Equation of symmetry, 

Step 2: Find the value of y at the point of symmetry
That is, we substitute x obtained above into the y and solve.

The maximum height of the diver is therefore 4 meters.
Its 5 because if u do 3x 5 it equals 15 then subtract 2 it gives u 13