Extra Credit Question: SUDOKU

Step 1: Starting Problem

Step 2: Explain carefully how to prove that there must be a 7 in cell E5

Step 3: Explain carefully how to prove that there must be a 7 in cell E5,

and the reduced options on cells C6,C5,D7

Step 4: Explain carefully how to prove that there must be a a 5 and a 7 in

the highlighted cells.

Step 5 : Complete the solution.