Question 1207820
To ignore denstities and choice between w/w, w/v;


60 volume units of 40 % solution;
Solution available to mix, 15%;
Mix result wanted, 25%.


v, amount of the 15% solution to add and mix:


{{{(60*0.4+0.15v)/(v+60)=0.25}}}--------this equation without explanation; based on thinking in decimal fractions; solve for v.




..... maybe a little explanation.


Amount of resulting solute:  {{{0.4*60+0.15v}}}


Amount of resulting mixture:  {{{v+60}}}


As a rational expression, if 25% solution is wanted, this is 0.25.
amount of solute as numerator and amount of final mixture as denominator
must be equal to 0.25.