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Scientist A has invented a device for cars to save petrol by 20%. Scientist B's invention saves 30%. Invention of scientist C save 40%. The three inventions are independently in effect. If all three devices are used, how much petrol can one save? |
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Answer» entist A has invented 20% Scientist B's invention 30% Invention of scientist C save 40%. all THREE DEVICES are used =20%+30%+40% =90% 90% PETROL can one saved |
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