Answer:
see attached diagram
Step-by-step explanation:
First, draw the dashed line 50x+150y=1500 (dashed because the inequality is without notion "or equal to"). You can do it finding x and y intercepts.
When x=0, then 150y=1500, y=10.
When y=0, then 50x=1500, x=30.
Connect points (0,10) and (30,0) to get needed dashed line.
Then determine which region (semiplane) you have to choose. Note that origin's coordinates (0,0) do not satisfy the inequality 50x + 150y>1500, because

This means that origin lies outside the needed region, so you have to choose the semiplane that do not contain origin (see attached diagram).
They are basically the same number
Answer:
It's a bit unclear with the table this way, but I count fifteen points, fifteen lines of the table, each a pair of numbers.
That's 15 degrees of freedom in the data. When modeling, each parameter in the model uses up one degree of freedom, so you'd use a smaller number of degrees of freedom when calculating t statistics, etc.
It would be B: a set of points that extends infinitely in two directions