It's answer will be 36x10^5
As we have
(4x10^10)(9x10^-5)
All terms of this expression are being multiplied
So we will solve it in two parts, simple terms and terms having powers
(4x9)(10^10x10^-5)
As we know when same terms having some powers are multiplied, their powers are added
(36)(10^(10-5))
(36)(10^5)
So it will become
36x10^5
