Eliza can iron a blouse in 15 minutes and a dress in 20 minutes. If she spends 2 hours ironing blouses and 3 hours ironing dresses, how many pieces of clothes did she iron? Let's be accurate as possible.
Since 60 minutes equal 1 hour, in 2 hours, Eliza ironed blouses for 2 x 60 = 120 minutes. Eliza can iron 120 / 15 = 8 blouses. Since 60 minutes equal 1 hour, in 3 hours, Eliza ironed dresses for 3 x 60 = 180 minutes. Eliza can iron 180 / 20 = 9 dresses. In total, Eliza ironed 8 + 9 = 17 pieces of clothes.
The answer: 17.