Steps to solve:
(4.7 x 10^4)(6.4 x 10^15)
~Combine like terms
(4.7 x 6.4)(10^4 x 10^15)
~Simplify
30.08 x 10^4+15
30.08 x 10^19
~Divide by 10 to get a number less then 10
30.08/10 x 10^19
3.008 x 10^20
Therefore, the answer is A) 3.008 x 10^20
Best of Luck!
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