The answers you could use are both the second and the forth. But mostly the fourth.
Have you ever heard the tragedy of darth plagues the wise

This is because you can at most, factor out x² and y³
There is not enough info to answer this question.
$45.50
2 bags = $7
13 bags=?
7÷2=3.5
3.50=1 bag
$3.50 × 13 bags = $45.50 for 13 bags of Doritos