Question 613565
1/2 is really 2^(-1), which is the multiplicative inverse of 2 (mod 5)


So we need to find a number that when you multiply it by 2, you'll get a result that is congruent to 1 (mod 5)



Notice how 2*3 = 6 = 1 (mod 5)


So 2^(-1) = 3


Using your notation of 1/2, this means 1/2 = <font color="red">3</font> (mod 5)