CANDIDATES take both the SUBJECTS.
PERCENTAGE of candidates who opted Physics = 65.8%
and percentage of candidates who opted Mathematics = 59.2%
x = (65.8 + 59.2 - 100)% = (125 - 100)% = 25%
Also, total number of candidates = 2000
Number of candidates who opted both the subjects
= 25 x 2000/100 = 500