Alamina occupies the region inside the circle x2 + y2 = 18y but outside the circle x2 + y2 = 81. find the center of mass if the density at any point is inversely proportional to its distance from the origin.

Dakota earned $7.50 in interest in account a and $18.75 in interest in account b after 15 months. if the simple interest rate is 4% for account a and 5% for account b, which account has the greater principal? explain. to make it a little easier, there is an image. good luck!