First find the total amount of paint Marla mixes by dividing the amount of blue paint by the percentage of the paint that's blue: 140 ounces / .7 = <<140/.7=200>>200 ounces

Then multiply the total amount of paint by the percentage that's white to find the number of white ounces: 200 ounces * 10% = <<200*10*.01=20>>20 ounces

# Answer

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<|im_start|>system
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<|im_start|>user
Marla is mixing a particular shade of lilac that's 70% blue paint, 20% red paint, and the rest white paint. If she adds 140 ounces of blue paint, how many ounces of white paint does she add?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
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user
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Marla is mixing a particular shade of lilac that's 70% blue paint, 20% red paint, and the rest white paint. If she adds 140 ounces of blue paint, how many ounces of white paint does she add?
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