Final answer:
The student's present marks are less than the previous year's score by 20%.
Step-by-step explanation:
Step 1:
Let's assume the student's score in the previous year was 100.
Step 2:
The score is dropped by 20%, which means it becomes 80 in the next year.
Step 3:
The student then scores 20% more in the next year. 20% of 80 is 16, so the student's score in the next year is 80 + 16 = 96.
Step 4:
To calculate the percentage difference, we can use the formula ((New score - Previous score)/Previous score) * 100. ((96-80)/80) * 100 = 20%, which means the student's present marks are 20% less than the previous year's score.
Answer:
The student's present marks are less than the previous year's score by 20%.