Population decrease In 1990, a rural area had 1200 bird species. If species of birds are becoming extinct at the rate of
1.5% per decade (10 years), how many bird species will there be
left in the year 2020?

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?