Answer:
80 cc.
Step-by-step explanation:
We work in amounts of salt in the solutions:
0.09x + 0.17*80= 0.13(x+ 80) where x is the required volume of 9% solution.
0.09x + 13.6 = 0.13x + 10.4
13.6 - 10.4 = 0.13x - 0.09x
3.2 = 0.04x
x = 3.2 / 0.04
x = 80
