Consider the question. Mason is cleaning out all the junk in his attic. 20% of the items are useful, 10% are valuable heirlooms, and 70% are junk. If Marcus's attic has 8 useful items in it, how many junk items does it have?
 If the answer is '28'; explain the reasoning:
First find the total number of items in the attic by dividing the number of useful items by the percentage of useful items: 8 items / .2 = 40 items. Then multiply the total number of items by the percentage that are junk to find the number of junk items: 40 items * .7 = 28 items.