<human>:  Jenna is adding black dots to a bunch of white blouses. Each blouse gets 20 dots, and each dot takes 10 ml of black dye. How many 400-ml bottles of dye does Jenna need to buy to dye 100 blouses?
<bot>: How many ml of dye does each blouse take? ** First find the amount of dye each blouse takes: 20 dots/blouse * 10 ml/dot = <<20*10=200>>200 ml/blouse
How many ml of dye does Jenna need to buy? ** Then multiply the dye used per blouse by the number of blouses to find the total amount of dye used: 200 ml/blouse * 100 blouses = <<200*100=20000>>20000 ml
How many bottles of dye does Jenna need to buy? ** Then divide the amount of dye needed by the amount of dye per bottle to find the number of bottles needed: 20000 ml / 400 ml/bottle = <<20000/400=50>>50 bottles
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