Here we have two complex numbers represented as a+bi and c+di.

By the rule of polynomial multiplications, the result will look like (ac-bd)+(ad+bc)i.

So this will be a new A+Bi which I represented in res_a+res_bi in below code.

```
def complexNumberMultiply(self, a, b):
m = a; n = b
a, b = m.replace("i", "").split("+")
c, d = n.replace("i", "").split("+")
a, b, c, d = int(a), int(b), int(c), int(d)
res_a = a*c-b*d
res_b = a*d+b*c
res = str(res_a) + "+" + str(res_b) + "i"
return res
```