If using the method of completing the square to solve the quadratic equation, which number would have to be added to “complete the square”? X^2+7x-4=0

Tom had a total of $220 and he spent $35 on a basketball ticket . what percent of his money did he have left?

George is putting trim around his rectangular deck, including the gate. he will need 44 feet of trim to do the entire deck. if the deck is 13 feet long, how wide is the deck?

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?