How do i do this and how could i learn to do these type of problems easier and faster

To answer the question about sneakers:

We know that the price we have now is only 75% of the original price. That would mean that the original price could be found by adding the extra 25%. Let's find 1%. You could also find 5%, 25%, or anything else that is easy for you, but we are going to do it as 1%.

Do the price divided by 75, and then multiply it by 100 to get the full price.

If you wanted an explanation on the one below, tell me.

Iknow one of the answers is a and maybe b but not 100% sure about b