What is the concentration of a tin(ll) chloride solution prepared from a sample of tin ore?

Problem
What is the concentration of a tin(ll) chloride solution prepared from a sample of tin ore?

 
Experimental Design
The potassium dichromate solution is first standardized by titration with 10.00 mL of an acidified 0.03 mol/L solution of the primary standard, iron(II) ammonium sulfate-6-water.  The standardized dichromate solution is then titrated against a sample of the acidified tin(II) chloride solution (You will do this step in the next question).

 
Evidence

TITRATION OF IRON(lI) SOLUTION

(volume of K2Cr2O7(aq) required to react with 10.00 ml of 0.03 mol/L Fe2+(aq))

Trial                                 1                   2                       3                         4
Final Buret Reading (ml)    13.8              24.4                  35.2                     45.9
Initial Buret Reading (ml)    2.3               13.8                  24.4                     35.2

Find the concentration of the Cr2O72-(aq) in mol/L:
 
I know this is a lot to ask but I am honestly so confused right now with what to do and how to do it! Please help!