Question 1052222
40% or 60% or anything more than about 38 % "saline" is nonsense.  You probably want more help with the Mathematics of the description than advice about the physics of it.


x and y for quantities of the starting materials.
{{{x+y=8}}}-----Mix your x and y liters to make a mixture of 8 liters.



Account for the "pure material".
{{{(40x+60y)/8=55}}}
and simplify this.
-
{{{(8x+12y)/8=11}}}


{{{(2x+3y)/2=11}}}


{{{2x+3y=22}}}------simplified from the percentage equation.



Now you have a system of two linear equations in two unknown variables.
{{{system(x+y=8,2x+3y=22)}}}