Can someone explain me this program?

Question

def change (P,Q=30):
P=P+Q
Q=P-Q
print(P,"#",Q)
return(P)
R=150
S=100
R=change(R,S)
print(R,"#",S)
S=change(S)

Output:
250#150
250#100
130#100

Answer 1

It is money making program. Dont use it )