Suppose a multi-programming operating system is allotting time slices of 50 milliseconds.?

If it normally takes 8 milliseconds to position a disk's read/write head over the desired track and another 17 milliseconds for the desired data to rotate around to the read/write head, how much of a program's time slice can be spent waiting for a read operation from a disk to take place? If the machine is capable of executing ten instructions each microsecond, how many instructions can be executed during this waiting period? Show the details of all calculations.