The motor of a fan turns a small wheel of radius rm = 2.23 cm. This wheel turns a belt, which is attached to a wheel of radius rf = 3.07 cm that is mounted to the axle of the fan blades. Measured from the center of this axle, the tip of the fan blades are at a distance rb = 11.7 cm. When the fan is in operation, the motor spins at an angular speed of ? = 1390 rpm. What is the tangential speed of the tips of the fan blades?