Please help meee :(

Dawn is selling her mp3 player for 3 4 of the original price. the original price for the mp3 player was $40. how much is she selling her mp3 player for?

Step by step explanation pls for 10 pts the length of a rectangular board is 3 feet less than twice its width. a second rectangular board is such that each of its dimensions is the reciprocal of the corresponding dimensions of the first rectangular board. if the perimeter of the second board is one-fifth the perimeter of the first, what is the perimeter of the first rectangular board?  

Allen's goal is to have between 1,500 and 1,600 bottles in his collection. write and solve a compound inequality to determine the number of weeks it will take allen to reach his goal. show your work. *