If Washington wins out they win the division. If Dallas wins out then they win the division. If the Eagles win out they would need Dallas to finish no better than 9-8,or go 1-4 over their last 5 games.
If Dallas wins 3 of their games, and one is against Washington, they win the division.
If Washington splits with Dallas and they both finish at 10-7, Washington wins the division with a better division record. For this to happen Dallas can only win 2 more games and Washington can only lose 1 more game.
If Dallas and the Eagles tie at 10-7, Dallas would win the division today by a better point differential. But the Eagles would have to win out to get to 10-7. If they do, they would eliminate Washington on their way to doing it.
If Dallas beats Washington and then the NY Giants, and the Eagles split with Washington, Dallas wins the division.
The key game for Dallas is the NY Giants. That is a must win game, especially if they lose to Washington. If they beat Washington and then the NY Giants, the Cowboys put a lot of pressure on the Eagles and WFT who must both win out - and they play each other twice.
That's math though. If Dallas loses to the WFT tomorrow they put all the pressure on themselves the next two weeks. Who knows what a lose would do to their psyche.