question: Lorraine and Colleen are trading stickers for buttons. Each large sticker is worth a large button or three small buttons. A small sticker is worth one small button. A large button is worth three small stickers. Lorraine starts with 30 small stickers and 40 large stickers. She trades 90% of her small stickers for large buttons. She trades 50% of her large stickers for large buttons and trades the rest of them for small buttons. How many buttons does she have by the end?
answer: She trades 27 small stickers because 30 x .9 = <<27=27>>27
  She gets 9 large buttons for these because 27 / 3 = <<27/3=9>>9
  She trades 20 large stickers for large buttons because 40 x .5 = 20
  She gets 20 large buttons for these because 20 / 1 = <<20/1=20>>20
  She trades 50% of her large stickers for small buttons because 100 - 50 = <<100-50=50>>50
  She trades 20 large stickers for small buttons because 40 x .5 = 20
  She gets 60 small buttons because 20 x 3 = <<20*3=60>>60
  She has 89 buttons at the end because 9 + 20 + 60 = <<9+20+60=89>>89
  #### 89