Step 1: Identify the placement of Biology. Since there are 3 exams after Biology, it must be on Monday.
Step 2: Since Physics and Mathematics are not conducted on Tuesday, the only subject left for Tuesday is English.
Step 3: Physics is not on Thursday, so it must be on Wednesday.
Step 4: The only remaining subject is Mathematics, which must be on Thursday.

Arun’s present age in years is 40% of Barun’s. In another few years, Arun’s age will be half of Barun’s. By what percentage will Barun’s age increase during this period?