b.9 x 10^4 is 18 times larger than 5 x 10^3
This is a simple matter of floating point division. So let's do that.
9 x 10^4 / 5 x 10^3
First, divide the significands. Giving
9 / 5 = 1.8
And subtract the exponents
4 - 3 = 1
So the result of the division is
1.8 x 10^1 which is 18. So 9x10^4 is 18 times larger than 5x10^3. Now looking at the available options, it's obvious that only "b" is correct.
