Ido not understand! i'd really appreciate

We cannot divide by zero.  Since x is the average price per favor, we regar x as a positive quantity.  Thus, eliminate the first choice (x<0).

For positive x, the curve is a parabolic shape with its vertex near to (0,0).  If x approaches 0 from the right, y increases without bound.  Note that x cannot be either zero or negative.  As x approaches infinity, 50/x approaches infinity (has no upper bound in theory).

We have to take that +3 into account.  For every input x value, there will be a corresponding y value.  To this y, in every case, add 3.

The range will be (3, infinity).  Again, this is "in theory."  The # of party favors that can be purchased is certainly nowhere near infinity.  What would be a reasonable answer to this "range" question?

First subtract 10 from both side
y^2+6y-16=0
(y+8)(y-2)=0
-8 and 2