If a divided by 7 has a remainder of 6, what is the remainder when 4a is divided by 7?

I will assume that the least number you're asking for is a positive number.

Then we have to find the smallest positive integer n that satisfies the simultaneous system of congruences

n = 4 mod 7,

n = 5 mod 8,

n = 6 mod 9

The correct answer is 3 hope i can answer more of your questions = {)