Question

in a class there are 40 students they drink either tea or coffee. 20 students drink coffee and 35 students drink tea. draw a venn diagram and how many drind both coffee and tea

Answer 1

tea = 35 coffee = 20
tea + coffee - both = 40 
⇒ 35+20 - both = 40
⇒ 55 - both = 40 
⇒ both = 15
SO 15 students drink both coffee &tea

Answer 2

if there are 40 students then how can you say that 20 drink tea & 35 tea because if both are added then it makes 55 but there are only 40 students in the class