Question

Keith want to create a drink that is 40% juice. How much of a 10% juice solution should he add to 100 milliliters of 100% grape juice to obtain the 40% mixture?

Answer 1

% times amount of each part = % times amount of mix 

x = amount of 10% 

100 = amount of 100% 

x + 100 = amount of 40% mix 

10x + 100(100) = 40(x + 100) 

10x + 10,000 = 40x + 4,000 

-10x - 4000.....-10x - 4000 
------------------------------------- 6000 = 30x 
so x = 6000 ÷ 30 = 200 mL