Question 732460
The actual values and items could be anything.


How many gallons, u,  of  L%  solution should be mixed with v gallons of  H%  solution to obtain a mixture that is T% solution ?


{{{highlight((Lu+Hv)/(u+v)=T)}}}.  Solve for u.
To begin, {{{Lu+Hv=T(u+v)}}}
{{{Lu+Hv=Tu+Tv}}}
{{{Lu-Tu=Tv-Hv}}}
You continue this until you have the formula for u...


Once you have a formula for u, you would just substitute the values given in the problem description to find how much is u.  The variables are these:


u = how many gallons of the 2% acid
v = 30 gallons of the 11% acid
L = 2%
H = 11%
T = 8%