Answer:
[tex]8\cdot 10^{700}[/tex]
Step-by-step explanation:
Since multiplication is commutative, you can rearrange this expression to simplify it.
[tex](4.5\cdot10^{400})(2.0\cdot10^{300}) = (4.5\cdot2.0)\cdot(10^{400}\cdot10^{300})=\boxed{8\cdot 10^{700}}[/tex]. Hope this helps, and comment below with more questions if this didn't make sense!
