<PRE><B>Question 1005187</B>
 How many liters of a 20% acid solution should be mixed with 30 liters of 50% acid solution in order to obtain a 40% solution.
-----
Equation:
acid + acid = acid
0.20x + 0.50*30 = 0.40(x+30)
-------
20x + 50*30 = 40x + 40*30
----
-20x = -10*30
x = 15 liters (amt. of 20% solution needed)
---------
Cheers,
Stan H.
----------------- </PRE>