Answer for someone u know who I'm talking about

David must install fencing around a lot that is shaped like a right angle. the side of lot that runs east-west is 200 ft long. the side of the lot runs north-south is 125 ft long. calculate how many feet of fencing he will need to surround the entire lot.

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?

What is the least common multiple for 6 and 8? what is the least common multiple for 4 and 12 ? what is the least common multiple for 11 and 12? what is the least common multiple for 3 and 6?