What is the absolute value of negative 11

Add the two expressions 3.8b - 7 and 2.9b + 9 enter your answer in simplified form

Linda loans her friend $250 with a 5% monthly intrest rate. how much was the whole loan?

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?