Question 365004
Let {{{A}}} be the amount of 100% acid, {{{B}}} the amount of 10% acid.
1.{{{A+B=90}}}
.
.
{{{100A+10B=75(90)}}}
2.{{{10A+B=675}}}
Subtract eq. 1 from eq. 2,
{{{10A+B-A-B=675-90}}}
{{{9A=585}}}
{{{highlight(A=65)}}}liters
Then from eq. 1,
{{{65+B=90}}}
{{{highlight(B=25)}}}liters