Hi can someone help me out. This is due by the end of the day. please tell me an explanation to the answer

Geometry answer picture question pls . reason and statements

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

An arc subtends a central angle measuring 7pi/4 radians what fraction of the circumference is this arc?