discrete mathematics - Which statements hold true for modular arithmetic?

I'm given a multiple choice problem with 4 statements that could be each true or false. To help determining which ones are true or false I did some example problems which I will list here. I have made some guesses, however I'm not too confident in them. Any help would be appreciated.

a) 50 mod 7 = 1 AND 15 mod 7 = 1

Note that 50 = 10*5 and 15 = 3*5

b) 10 mod 7 = 3 AND 3 mod 7 = 3

c) 24 mod 11 = 2 AND 68 mod 11 = 2

Note that 24 = 6*4 and 68 = 17*4

d) 6 mod 11 = 6 AND 17 mod 11 = 6

e) 12 mod 5 = 2 AND 27 mod 5 = 2

Note that 12 = 4*3 and 27 = 9*3

f) 4 mod 5 = 4 AND 9 mod 5 = 4

g) 30 mod 3 = 0 AND 45 mod 3 = 0

Note that 30 = 6*5 and 45 = 9*5

h) 6 mod 3 = 0 AND 9 mod 3 = 0

i) 52 mod 7 = 3 AND 80 mod 7 = 3

Note that 52 = 13*4 and 80 = 20*4

j) 13 mod 7 = 6 AND 20 mod 7 = 6

Assume n represents the modulus, k represents a common factor and a,b are integers.

1. If n and k are relatively prime and if ak mod n = bk mod n, then a=b

2. If n and k are relatively prime and if ak mod n = bk mod n, then ak=bk

3. If n and k are relatively prime and if ak mod n = bk mod n, then a mod n = b mod n

4. If n and k are relatively prime and if ak mod n = bk mod n, then a mod n = ak mod n

MY ANSWERS: I think 1, 2, and 4 are all false, while 3 is true.