Louise is organizing her pencils, and decides she wants her boxes arranged by color. Each box holds 20 pencils each. She has 20 red pencils, twice as many blue pencils, 40 yellow pencils, and has as many green pencils as she has red and blue pencils combined. How many boxes does Louise need? Let's answer step by step:
Louise has 20 red pencils * 2 = 40 blue pencils. She therefore has 20 red pencils + 40 blue pencils = 60 green pencils. In total, she has 20 red pencils + 40 blue pencils + 60 green pencils + 40 yellow pencils = 160 pencils. As each box holds 20 pencils, she needs 160 pencils / 20 pencils / box = 8 boxes. The answer: 8.