Hi there, maybe dumb question but how would I find the initial concentration of Fe^3+??

Question

In lab, we mixed these reactants into one test tube:
-0.50mL of 0.0025M Fe(NO3)3
-0.50mL of 0.0025M KSCN
-2.50mL of 0.10M HNO3

The net ionic equation for the experiment is:
Fe^3+(aq) + SCN^-(aq) <-> FeSCN^2+(aq)

Molarity is mol/volume in L, but we're given 0.0025mol of Fe in this case, but what volume would I use to divide in order to find the initial concentration of Fe^3+? Would I use the volume of the Fe^3+ added into the mix or the total volume of the entire test tube??

Thanks in advance