My team has a ranking of 1700. We lose to a team that has a ranking of 1600. What happens to our ranking? Our opponent’s ranking?

In this case, your team would lose 20 ranking points, and would have a new ranking of 1680. Your opponent would gain 20 ranking points, and would have a new ranking of 1620. The key feature to appreciate is that lower-ranked teams have more to gain from winning, and higher-ranked teams have more to risk from losing.