Question 356576
Let A be the amount of 90% mixture, B the amount of 75% mixture.
Volume:
1.{{{A+B=600}}}
Concentration:
{{{90A+75B=85(600)}}}
2.{{{18A+15B=10200}}}
Multiply eq. 1 by (-15) and add to eq. 2 to eliminate B and solve for A.
{{{-15A-15B+18A+15B=-9000+10200}}}
{{{3A=1200}}}
{{{highlight(A=400)}}}ml
Then from eq. 1,
{{{400+B=600}}}
{{{highlight(B=200)}}}ml