The question is a trick question in that it gives you the concentration of the solution in terms of a ion inside it, instead of the solution as a whole.
Co3+ + 3F-
m= ?
M= 115.93
V= 0.065L
c= 0.2432
n=cv
= 0.2432 x 0.065
= 0.015808 of F3 ions.
Divide this by 3 to get the amount for...