You can use this calculator to obtain a pair of Bézout's coefficients as well as the general form of the coefficients. Some theory can be found below the calculator
Bézout's identity and Bézout's coefficients
To recap, Bézout's identity (aka Bézout's lemma) is the following statement:
Let a and b be integers with the greatest common divisor d. Then, there exist integers x and y such that ax + by = d. More generally, the integers of the form ax + by are exactly the multiples of d.
If d is the greatest common divisor of integers a and b, and x, y is any pair of Bézout's coefficients, the general form of Bézout's coefficients is
and the general form of Bézout's identity is