Answer:
We'll be making 35 liters of 19% glucose.
How much of a 15% solution and a 35% solution do we mix in order to get 35 liters of a 19% glucose solution?
X = liters of 15% and Y = liters of 35%
(.15 X + .35 Y) / 35 = .19
The number of Y liters will equal (35 -X) so the equation becomes
(.15 X + .35 *(35-X) ) / 35 = .19
(.15X + 12.25 -.35X) / 35 = .19
(-.20 X / 35) + (12.25 / 35) = .19
(-.20 X / 35) + .35 = .19
(-.20 X / 35) = -.16
-.20X = -5.6
X = 28 liters of 15% and
Y = 7 liters of 35% glucose
Answer is "c" 28 liters