Question 370172
Let A be the amount of 30% HCl, B the amount of 45% HCl.
1.{{{A+B=50}}}
.
.
{{{30A+45B=35(50)}}}
2.{{{6A+9B=350}}}
Multiply eq. 1 by (-6) and add to eq. 2,
{{{-6A-6B+6A+9B=-300+350}}}
{{{3B=50}}}
{{{highlight(B=50/3)}}}liters
Then from eq. 1,
{{{A+50/3=50}}}
{{{A=150/3-50/3}}}
{{{highlight(A=100/3)}}}liters