Disk rolls around another disk

The radius of the disk A is 4 cm and that of the disk B is 3 cm.

As shown in a figure, the arrow is written on the disk B.

The disk A is not moved.

The disk B rolls clockwise without sliding along with the circumference of the disk A until the arrow and the disk B come back to the original position same as in the figure.

Find the number of times that the disk B rotates around the center B.

Answer