Basically you’re doing basic algebra. You take the “11m” and subtract it to the positive (1) m. And you basically should see 1m-11m EQUALING -10m. Don’t let the negatives confuse you.
Then you take the 20 and subtract it to -6. It should look like: -6-20 = -26.
Then divide-10 to -26, then you should get 2.6. And yes positive!!