Question 991518
Here is setting-up and resolution for the first question:


Let v be how much of the 30% solution to use.
{{{AmountOfAcid/AmountOfMixture=FractionAcid}}}


But using percents on both sides,
{{{(1*10+30v)/(v+1)=22}}}
-
{{{(30v+10)/(v+1)=22}}}
{{{30v+10=22(v+1)}}}
{{{30v+10=22v+22}}}
{{{8v+10=22}}}
{{{8v=12}}}
{{{v=12/8}}}
{{{highlight(v=1&1/2)}}}, liters of the 30% solution.