Answer:
c. 28 liters
Explanation:
Given tha tJanet is mixing a 15% glucose solution with a 35% glucose solution. This mixture produces 35 liters of a 19% glucose solution. Now we need to find about how many liters of the 15% solution is Januet using in the mixture.
Let the number of liters of the 15% solution is Januet using in the mixture = x
Let the number of liters of the 35% solution is Januet using in the mixture = y
Then we get equations:
x+y=35...(i)
and
(15% of x) + (35% of y) = 19% of 35.
or
0.15x+0.35y=0.19(35)
15x+35y=19(35)
3x+7y=19(7)
3x+7y=133 ...(ii)
solve (i) for x
x+y=35
x=35-y...(iii)
Plug (iii) into (ii)
3x+7y=133
3(35-y)+7y=133
105-3y+7y=133
105+4y=133
4y=133-105
4y=28
y=28/4
y=7
plug y=7 into (iii)
x=35-y=35-7=28
Hence final answer is c. 28 liters