80 mililiters of the 10% solution
120 mililiters of the 30% solution
Explanation:
let the amount of solution for the 10% = x
let the amount of solution for the 30% = y
The sum of the amount for the mixture of 10% solution and amount for the 30% solution = 200 mililiters
x + y = 200 ...(1)
In terms of fraction for each solution:
fraction of the 10% solution + fraction of the 30% solution = fraction of the mixture
percentage of the solution of the mixture = 22%
fraction of the 10% solution = 10% (x) = 0.1(x) = 0.1x
fraction of the 30% solution = 30%(y) = 0.3(y) = 0.3y
fraction of the mixture = 22%(200) = 0.22(200)
substitute the above into the equation for fraction:
0.1x + 0.3y = 0.22(200)
0.1x + 0.3y = 44 ...(2)
combine both equatons:
x + y = 200 ...(1)
0.1x + 0.3y = 44 ...(2)
Using substitution method to solve the equations:
from equation 1, let's make x the subject of formula:
x = 200 - y
substitute for x in equation (2):
0.1(200 - y) + 0.3y = 44
20 - 0.1y + 0.3y = 44
20 + 0.2y = 44
0.2y = 44 - 20
0.2y = 24
divide both sides by 0.2:
0.2y/0.2 = 24/0.2
y = 120
sustitute for y in equation (1):
x + 120 = 200
x = 200 - 120
x = 80
Hence, James must mix:
80 mililiters of the 10% solution
120 mililiters of the 30% solution
