Answer:
1.83×[tex]10^{-9}[/tex]
Step-by-step explanation:
The exponent on the base of ten is -9 for both. The easiest way to do this when that is the case is to factor it out:
[tex]10^{-9}(6.33-4.5)[/tex]
and then perform the subtraction to give you
1.83×[tex]10^{-9}[/tex]