Can y’all please help me I’m doing a game for science C2H4 + 3 02

An object moves from the position +34m to the position -15m in 15 seconds. what is it's total displacement? what is it's average velocity?

15. give an example for some particles or waves that are moving faster than light in everyday life 16. what is a laser? 17. what is an oscilloscope? 18. what does it means practically that nothing is faster than light in vacuum? 19. what is vacuum?

Mixing salt in water is an example of physical change