Answer:
66 2/3 mL
Step-by-step explanation:
Let v represent the volume in mL of added 30% solution. Then the amount of salt in the mix is ...
0.10×100 +0.30×v = 0.18(100 +v)
0.12v = 0.08(100) . . . . .subtract (0.18v +0.10×100)
v = 8/0.12 . . . . . . . . . . . divide by the coefficient of v
v = 66 2/3 . . . . mL
Adding 66 2/3 mL of 30% salt solution to 100 mL of 10% salt solution will make 166 2/3 mL of 18% salt solution.
