Question 337049
Let A be the amount of 60% solution and B the amount of 0% solution (pure water).
1.{{{A+B=40}}}
.
.
.
{{{60*A+0*B=10(40)}}}
2.{{{60A=400}}}
{{{A=400/60}}}
{{{highlight(A=20/3)}}}
Then from eq. 1,
{{{20/3+B=40}}}
{{{B=120/3-20/3}}}
{{{highlight(B=100/3)}}}