Answer:
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Way 1: Find what 40% of 30 is and subtracting it from 30, leaving 60% of 30 left:
40% of 30 is 0.4*30 = 12, 30 - 12 = 18
Way 2: Subtract 40% from 100% and multiply it by 30: 100% - 40% = 1 - 0.4 = .6, 0.6*30 = 18
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