Question 1154192
Two-part mixture can generally be solved as:
How many liters of L% solution be added to H% solution to produce M liters of T% solution?


v, volume of the H% solution
M-v volume of the L% solution


{{{highlight_green(Hv+L(M-v)=TM)}}}
-
{{{Hv+LM-Lv=TM}}}
{{{Hv-Lv=TM-LM}}}
{{{v(H-L)=M(T-L)}}}
{{{highlight(v=M((T-L)/(H-L)))}}}


Substitute your given {{{system(M=8,T=30,L=10,H=40)}}}, and evaluate v.