Question 324803
Let A be the amount of 35% solution, B the amount of 50% solution.
{{{A+B=10}}}
{{{35A+50B=40(10)=400}}}
Multiply eq. 1 by -50 and add to eq. 2 to eliminate B.
{{{-50A-50B+35A+50B=-500+400}}}
{{{-15A=-100}}}
{{{highlight(A=20/3)}}}
Then from eq. 1,
{{{20/3+B=30/3}}}
{{{highlight(B=10/3)}}}