We'll do the first one. I can't read the variable, but it looks like a

so that's what I'll use, but it doesn't matter.
First, get the variable by itself:

You get that before you multiply each side by two.
Now, you color the line so that all values that are less than 6 are shaded, so you put an open circle at 6 since it's not included and then you shade everything to the left.
The answer is B.
This is because A is incorrect, Zach number of minutes didnt increase by an equal factor every month.
C and D are incorrect, Victoria's methods aren't exponential, but Zach's are.
So that leaves the only reasonable answer which is B.