Answer:
7.555×10^7.
Explanation:
We need to make sure that they have the same exponent. We can do this by adjusting the decimal point in the first number to subtract:
(7.8×10^7)−(2.45×10^6)
(7.8×10^7)−(0.245×10^7) (since 2.45 = 0.245*10)
Now, we can subtract the two numbers by taking common:
10^7*(7.8-0.245)
7.555*10^7
Therefore, the difference between the two numbers in scientific notation is 7.555×10^7.