Question

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?

Answer 1

Scientist 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

Answer 2

Answer: 20 + 30+ 40 = 90

90% petrol can one save

hope it's helpful