Both traveled the same speed: 3cm/3s= 1m/s and 6cm/6s= 1m/s
The answer would be 12, 8, 0, -3, -4.
The answer is that because 12 is a positive number so that's higher than negative, 8 goes second because its positive and higher than the others, 0 is third because negatives numbers are LOWER than 0, not higher, -3 is next because higher negative numbers are always lower, not greater than smaller numbers because -8 is LOWER than -4 since its on the left of a number line.
Fermat's little theorem states that

≡a mod p
If we divide both sides by a, then

≡1 mod p
=>

≡1 mod 17

≡1 mod 17
Rewrite

mod 17 as

mod 17
and apply Fermat's little theorem

mod 17
=>

mod 17
So we conclude that

≡1 mod 17