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.

29933333.33

step-by-step explanation:

6×10=604000000÷60=66666.6666766666.6667×449=29933333.33