Use the Euclidean algorithm to find integers x and y such that 164x+39y=1. Note that while there are many pairs of integers x and y that satisfy this equation, there is only one pair that comes from using the Euclidean algorithm.
x==5 and y == - 21
You have to use the "Extended Euclidean Algorithm", which is a long process:
(164 * 5) + (39 * -21) = 1