Let A denotes students passed in English.
B denotes students passed in Science.
and C denotes students passed in Mathematics.
|A| =80
|B| =60
|C| =50
|AՈB| =30
|AՈC| =15
|BՈC| =20
|A U B U C|=150
|AՈBՈC| =10
Students passed in at least one subjects
=|AՈB|+|AՈC|+|BՈC|
=30+15+20
=65
Hence, students passed in atleast one subject are 65
Students passed in English only
Passed in English only=|A|-[|AՈB|+|AՈC|+
=|A|-[|B|+|C|-|B Ո C|+|AՈBՈC|]
=80-[30+15+10]
=25
Hence, students passed in English only are 25.
Students failed in all three subjects
|A ̅ՈB ̅ՈC ̅|=150-(80+60+50) + (30+15+20)-10=60-62+20-2=10
So, 10 students failed in all three subjects.