Answer
--Recursive algorithm for computing the greatest common divisor of two non negative integers a and b with a < b using the fact that
gcd(a, b) = gcd(a, b − a).
Work Step by Step
--procedure gcd(a, b: nonnegative integers)
-{a < b assumed to hold}
-if a = 0 then return b
-else if a = b − a then return a
-else if a < b − a then return gcd(a, b − a)
-else return gcd(b − a, a)
