word problem

Question

Mrs.Gargantua thinks she finally may have found a medicine which will remove the blackness from her teeth. But first she has to mix a liquid containing 4% reactor fuel with a liquid containing 20% reactor fuel to create a 6 ounce liquid containing 8% reactor fuel. How many ounces of the 4% liquid must she use? (round your answer to the nearest one decimal place (tenths).)

Answer 1

x = amount of 4% fuel

6 - x = amount of 20% fuel

 

0.04x + 0.2(6 - x) = 0.08(6)       Multiply both sides by 100 to remove the decimals

4x + 20(6 - x) = 8(6)

4x + 120 - 20x = 48

-16x + 120 = 48

-16x = -72

x = 4.5

 

She should used 4.5 ounces of the 4% and 1.5 ounces of the 20%.