Question 743709
Pure acid would be 100%.  


How much as the quantity v of pure material should be mixed with u gallons of a L% solution in order to get a T% solution?


Known: u, L, T
Unknown: v


EQUATION:
{{{(uL+v*100)/(u+v)=T}}}
{{{uL+v*100=Tu+Tv}}}
{{{v*100=Tu+Tv-uL}}}
{{{v*100-Tv=Tu-uL}}}
{{{v(100-T)=u(T-L)}}}
{{{highlight(v=u*((T-L)/(100-L)))}}}


FIND VALUE FOR v:
Substitute the values from the original problem description and evaluate.