Which problem can be solved using this inequality?

x + 5 ≤ 20
a.
beth is purchasing school supplies. she knows that the price for her pencil case is $15. she only has $20 to spend. how much money will she have left after buying the pencil case?
b.
beth is purchasing school supplies. she knows that the price for her pencil case is less than $5. she only has $20 to spend. how much money will she have left to spend after buying the pencil case?
c.
beth is purchasing school supplies. she knows that the price for her pencil case is $5 more than the cost of a book bag. she only has $20 to spend. does beth have enough money to buy the pencil case and book bag?
d.
beth is purchasing school supplies. she knows that the price for her pencil case is $5. she only has $20 to spend. what is the most amount of money she can spend on the remaining supplies?