SOLUTION: A low grade of oil contains 2.5% of an additive and a high grade of oil contains 7.5% of an additive. How many liters of the 7.5% additive oil must be added to 500 L of the 2.5% ad

Algebra ->  Human-and-algebraic-language -> SOLUTION: A low grade of oil contains 2.5% of an additive and a high grade of oil contains 7.5% of an additive. How many liters of the 7.5% additive oil must be added to 500 L of the 2.5% ad      Log On


   

Question 1193722: A low grade of oil contains 2.5% of an additive and a high grade of oil contains 7.5% of an additive. How many liters of the 7.5% additive oil must be added to 500 L of the 2.5% additive oil to get a mixture with 6.5% of the additive?
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
500 L of 2.5% additive
x Liters of the 7.5% additive
Mixture result 6.5% additive

Account for the amount of the pure additive.
2.5%2A500%2B7.5x=6.5%28x%2B500%29
Solve!

Do all computations LAST.

7.5x%2B2.5%2A500=6.5x%2B6.5%2A500
7.5x-6.5x=6.5%2A500-2.5%2A500
%287.5-6.5%29x=500%286.5-2.5%29
highlight_green%28x=500%28%286.5-2.5%29%2F%287.5-6.5%29%29%29
x=500%284%2F1%29

highlight%28x=2000%29

CHECK - Does this value work?
2.5%2A500%2B7.5%2A2000=6.5%282500%29
1250%2B15000=16250
16250=16250
YES