Which of the following steps is necessary to add (2.3 x 10^3) and (5.4 x 10^4)?

Calculate the result of (6.75 x 10^6) + (3.45 x 10^7) ensuring the answer has the least number of decimal places.

What is the result of (9.0 x 10^5) - (2.5 x 10^4)?

If the coefficient of a number in scientific notation is decreased, what happens to the exponent to maintain the same value?