Answer:
[tex]6.31*10^{-4} \\8.1*10^{9}[/tex]
Step-by-step explanation:
0.00065 - 0.000019 = 0.000631
Move back 4 decimal places.
5300000000 + 2800000000 = 8100000000
Move forward 9 decimal places.
Hope this helps! If you need help on converting them back to scientific notation or getting the value of the exponent, just ask!