Answer: n=1000
Explanation:
the original problem: 8.9×10⁷=[1×10³][8.9×10n]
then swap the side that 8.9×10⁷= is on so that is looks like this: [1×10³][8.9×10n]=8.9×10⁷
then multiply both sides by ten: [1×10³][8.9×10n]×10=8.9×10⁷×10
then simplify: 890000n=890000000
then divide both sides by 890000 and simplify: n=1000