Let 
be the volume of 20% solution, 
the volume of the 60% solution. We want a total volume of 400 mL in the final mixture, so
Each mL of either solution will contribute a corresponding concentration, and in the final mixture we want the 400 mL to have a 40% concentration, which means we should also have
Solve the system and we get 
.
Answer:-22
Step-by-step explanation:
5 times -3 equals -15, and the combine it with -7 to get -22
L=(P-2W)/2 HOPE I HELPED YA :)
Convert all the equations to slope-intercept form:
Lines A, B and C have the same slope as the line 2y-4x=3, so they are parallel and don't intersect it.
Line D has another slope, so it intersects the line 2y-4x=3.
The answer is D.
6.666666666667............
