Question 815286
100*{amount of pure acid}/{amount of solution}={percentage concentration}


Let u = how many liters of the 10% acid
Let v = how many liters of the 60% acid
Wanting 20 liters of acid solution, {{{u+v=20}}}.


Using the percentage concentrations,
{{{10u+60v}}} is how much of the actual pure acid; this is in scaled-up form, since the percent concentrations are 100 times larger than their fractional meanings.


{{{highlight((10u+60v)/20=50)}}}  and {{{highlight(u+v=20)}}};
Solve the system for u and v.