She received $2
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8x2= 16
So if 8 yuan equals $1 then 16 divided by 8 would be $2, hope this helped.
Let's say "c" is a constant, hmmmm any constant, for any value whatsoever of "x", "y" is always that constant, for example, say c = 3, thus y = 3, so a table for it will look like

now, if you plot those points, it'd looks like the picture below.
The forth picture is the one that represents 4.5
Let
be the time it takes for pumps A, B, and C (respectively) to fill 1 tank. Then

Now,

Then

This means

and

Working together, all 3 pumps would operate at a rate of

or 1 tank in 1 hour, so the answer is D.