18) Value of b is : 
Option A is correct.
19) Option C is correct.
Step-by-step explanation:
18) We need to find the value of b.
The given equation is:

Solving to find the value of b:

So value of b is : 
Option A is correct.
19) We need to find the correct graph of the equation:

Solving:

The values of y will be less than three. As y < 3 so, the circle on y is not filled.
So. Option C is correct.
Keywords: Solving Inequalities
Learn more about Solving Inequalities at:
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Answer:
Step-by-step explanation:
797.2
A function will not have any repeating x values....it can have repeating y values, but all the x values have to be different for it to be a function.
A is a function because all the x values are a different number
B is not a function because u have repeating x values...u have repeating 4's and repeating 9's
The bacteria at the end of 22 hours is 2,480