Question 1030915
<pre>
L     low     15%
m     medium  20%
h     high    25%</pre>

Twice as much of the 20% as the combined quantities of the 15% and 25%.
{{{highlight_green(m=2(L+h))}}}



ACCOUNT VOLUME OF MIX
{{{L+m+h=350}}}, in unit of quarts.


ACCOUNT CONCENTRATION OF MIX
{{{(15L+20m+25h)/350=19.5}}}, both members in percent.


Next in the process should be substitute for m in both accounting equations, and simplify each of these equations; and solve the resulting two-variable system of the two equations, using variables, L and h.