How much closer to the sun is one planet than the other?

C. 7.79 x 10^8

Step-by-step explanation:

Your Equation: (eight-point-one multiplied by ten to the eighth power) subtracted by (nine-point-one multiplied by ten to the seventh power)

so first we find out how much are in the parentheses :D

(8.7 x 10^8) = 870,000,000

(9.1 x 10^7) = 91,000,000

now you subtract 870,000,000 by 91,000,000.

 870,000,000

-    91,000,000

 779,000,000

converted back to standard form...

7.79 x 10^8

(seven and seventy-ninths multiplied by ten to the eighth power)

<3 Enjoy,

    Dea