Question

Find all replacements (less than the modulus. for the question mark that make the statement true. 7 + ? ≡ 3 (mod 8)
A. 7

B. 5

C. 4

D. 2

Answer 1

7 ≡ -1 (mod 8)

So

7 + x ≡ 3 (mod 8)

is the same as

-1+x ≡ 3 (mod 8)

Do you see what to do now?

Answer 2

so the answer is C. 4 ?

Answer 3

you got it

Answer 4

yay thankyou!

Answer 5

you're welcome, hopefully you see how 7 ≡ -1 (mod 8) ?