This problem is on the circular motion.
Assuming a basis of 1 sec, there would be 6 revolutions, which is equivalent to 6 circumference of the pulley. One revolution means one circumference, which is 2(pi)(10cm) or 20(pi) cm.
Therefore, linear speed is 6(20)(pi) cm/s or 376.99 cm/s or 3.77 m/s