Final answer:
After completing 25% of the prescriptions, 100 in total, there are still 300 prescriptions left to fill on the shift.
Step-by-step explanation:
If you have completed 25% of the 400 prescriptions, then the number of prescriptions filled is 25% of 400. To find this, you multiply 400 by 0.25, which gives you 100. Therefore, you have completed 100 prescriptions. To find out how many prescriptions are left to fill, you subtract the number you have already filled (100) from the total number (400).400 - 100 = 300 prescriptions are left to fill on that shift.