Depth and height changes

Think of a number line. Moving up adds, and moving down subtracts.

1. A submarine is at −11 m (below sea level means negative). It rises 4 m. What is its new position in metres?
2. A submarine is at 13 m (below sea level means negative). It rises 7 m. What is its new position in metres?
3. A submarine is at −15 m (below sea level means negative). It rises 10 m. What is its new position in metres?
4. A submarine is at 15 m (below sea level means negative). It rises 10 m. What is its new position in metres?
5. A submarine is at −13 m (below sea level means negative). It rises 16 m. What is its new position in metres?
6. A submarine is at 22 m (below sea level means negative). It rises 9 m. What is its new position in metres?
7. A submarine is at −7 m (below sea level means negative). It dives 3 m. What is its new position in metres?
8. A submarine is at 18 m (below sea level means negative). It dives 17 m. What is its new position in metres?
9. A submarine is at 39 m (below sea level means negative). It dives 49 m. What is its new position in metres?
10. A submarine is at −37 m (below sea level means negative). It rises 16 m. What is its new position in metres?
11. A submarine is at −24 m (below sea level means negative). It dives 39 m. What is its new position in metres?
12. A submarine is at 1 m (below sea level means negative). It rises 56 m. What is its new position in metres?
13. A submarine is at 70 m (below sea level means negative). It rises 89 m. What is its new position in metres?
14. A submarine is at 63 m (below sea level means negative). It rises 46 m. What is its new position in metres?
15. A submarine is at 94 m (below sea level means negative). It rises 52 m. What is its new position in metres?
16. A submarine is at 67 m (below sea level means negative). It rises 82 m. What is its new position in metres?
17. A submarine is at 168 m (below sea level means negative). It rises 167 m. What is its new position in metres?
18. A submarine is at −99 m (below sea level means negative). It rises 100 m. What is its new position in metres?
19. A submarine is at 254 m (below sea level means negative). It dives 98 m. What is its new position in metres?
20. A submarine is at 271 m (below sea level means negative). It rises 194 m. What is its new position in metres?