If using the method of completing the square to solve the quadratic equation x^2-15x-10=0x 2 −15x−10=0, which number would have to be added to "complete the square"?

Me. drysdale earned 906.25 in interest in one year on money that he had deposited in his local bank if the bank paid an interest rate of 6.25% how much money did mr. drysdale deposit

Two lines parallel to the same plane are parallel to eachother

Ineed to know the answer to this algebra question.