Answer:
f(x)=(x-6)(x-(-7))
Step-by-step explanation:
Foiled:
0 = x + x - 42
Class B has the most consistant sleep because there is less of a difference between 6.87 and 3.65 than the other classes.
Step-by-step explanation:
to work out gradient
change in y ÷ change in x
first lines gradient
(7 - - 8) ÷ (7 - 7) = 0
second lines gradient
(7 - 7) ÷ (9 - - 6) = 0



There is a bit more to the answer but it just explains a bit more that this question does not ask for.
Hope this helps!