Question 150522
a plant manager needs a solution of 77% herbicide to be mixed with a solution of 67% herbicide to form 30 liters of 74% solution. How many liters of the 77% solution must he use?


x=liters of 77%
30-x=liters of 67%
coefficient=percent


77x+67(30-x)=74(30)------------------------solution of 77% herbicide mixed with a solution of 67% herbicide = 30 liters of 74% solution. 



Distribute
77x+2010-67x=2220


Combine like terms
10x+2010=2220


Subtract 2010 from both sides
10x=210


Divide by 10
x=21


x=liters of 77%
30-x=liters of 67%


Answer:
liters of 77%=21
liters of 67%=9