Now we can see the blue cell that shares the common row with the fourth green cell must be 7 since it is the only place the digit 7 can go in this row. Then the fourth green cell that shares the common column with the third green cell cannot be 7. The third green cell that shares the common row with the second green cell must be 7. The second green cell that shares the common column with the first green cell must be 4.
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