Question 1208408
bottle c, 80% HCl
bottle d, 30% HCl
result to become mix to have 10 liter of 60% HCl
System of equations?  This should be done in one if you see how.


The pure HCl,  {{{0.8c+0.3d=1*0.6}}} but factor 1 does not give anything more.
{{{0.8c+0.3d=0.6}}}
{{{8c+3d=6}}}



Also c and d together must be 1 liter.
{{{c+d=1}}}


Good system for you:
{{{system(8c+3d=6,c+d=1)}}}


Work the rest from that.