Justin is making snowballs to build a fort on the winter break. justin can build 15 snowballs in an hour. how long will it take him to build 210 snowballs ?

I'm so close to finishing all these.

Can any one me with the answers to these questions asap?

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?