Answer:
I was going to give you the paper where I saw it but since you are not giving enough points I can not give you so I am only going to give you some of these that are here sorry
Explanation:
1.

x=5

7.
5,12,13
9.

Hdghehwhevevwgwhhwvsvsvsiosjwbwbwhshbshs
Distance=2m
because 200cm = 2m
so 4m-2m=2m
Coals energy is affordable and it is easy to burn.
Answer:
wavelength = v/f or wavelength equals to velocity over frequency
frequency= v/w or velocity over wavelength
frequency= 1/p or one over period or time