Amelia spent an hour an a half on a drawing. At the end she said that it was 75% done. How much time do she needs and how much time will it take her in total?

You can think of an hour and a half as 75% itself already because you have 3/4 or three thirty minute periods. So every 1/4 is a 30 minute period, and if you multiply 1/4 by 4 you get 4/4 which you ten can convert to 2 hours or 4, 30 minute time periods. (I'm sorry if I explained this in a very confusing manner). It will take Amelia 2 hours in total to finish her drawing.