What is the third term of the sequence ? an=3•2^ (n-1)

Can somebody 1. what is the formula for finding the vertical distance between two points on a coordinate plane?

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?

Jayne is studying urban planning and finds that her town is decreasing in population by 3% each year. the population of her town is changing by a constant rate. true or false?