<PRE><B>Question 211083</B>
we wish to obtain a 40% solution of nitric acid by mixing a 20% solution and a 70% solution of the acid. 
what percentages of the final solution should be taken from the 20% and 70% solutions
:
It does not give the amt of final solution to be made. 
Assume it is 100 units, easy to change amt to per cent.
:
Let x = amt of 70% solution used
then
(100-x) = amt of 20% solution
:
A typical mixture equation;
.7x + .2(100 - x) = .4(100)
.7x + 20 - .2x = 40
.7x - .2x = 40 - 20
.5x = 20
x = {{{20/.5}}} 
x = 40 units of 70% solution
and
100 - 40 = 60 units of 20% solution
:
We can say we will take 40% from the 70% solution
and take 60% from the 20% solution</PRE>