Question 820344
u = volume of the 10% solution
v = volume of the 50% solution


{{{(10u+50v)/(400)=40}}} and {{{u+v=400}}}
Solve for u and v.


First simplify the rational equation:
{{{10(u+5v)=16000}}}
{{{highlight_green(u+5v=1600)}}}
Next, for convenience, subtract the "400" equation from this simplified "1600" equation and solve for v; and then use either equation to finish solving for the value of u.