question: A farmer has 900 eggs. He placed them on a tray, which holds 30 eggs each. How much will the farmer earn if he sells it for $2.5 per tray?
answer: There are 900 / 30 = <<900/30=30>>30 trays that hold 900 eggs.
  So, the farmer will earn 30 x $2.5 = $<<30*2.5=75>>75 if he sells it per tray.
  #### 75