Please answer this one as well

Which spreadsheet would be used to compute the first nine terms of the geometric sequence a^n=32•(1/2)n-1

Suppose that sahil knows that 45 people with ages of 18 to 29 voted. without using a calculator, he quickly says then 135 people with ages of 30to 49 voted. is he correct? how might sohil have come up with his answer so quickly?

Write as a product: ac^2–ad+c^3–cd–bc^2+bd