13. D. going 10km upstream
14. A. {-12, -11, -10, -9, -8, -7, -6, -5, -4}
15. B. 30, 18, 5, -10, -28
16. D. -25 ÷ -5 = -5
17. A. 12 ft.
18. A. -60 or 60 feet below the surface of the water
19. A. 5
20. C. 10 units left of -15 = -25
Hope it can help :)
