Question

7x = 6 mod 5. Then the value of x is

(a) 2

(b) 3

(c) 4

(d) 5

The question was posed to me during an interview.

I'm obligated to ask this question of Polynomial and Modular Arithmetic- III in section Basic Concepts in Number Theory and Finite Fields of Cryptograph & Network Security

Answer 1

The correct answer is (b) 3

To explain I would say: 7 x 3 mod 5 = 6 mod 5 = 1.