solution
We can set up the following info:
x 0 1 2 3 4 5
y 18 20 22 23 25 22
And we can create an equation given by:
y = mx + b
And we have the following:
y= 19.095+ 1.028x
Then we can replace the value for 7pm at x= 9
y = 1.028*9 + 19.095 = 28.347
For the quadratic fit we got:
y = 17.607 + 3.2607x - 0.446 x^2