Start CAT Reasoning preparation free Like it? Continue at just ₹29/month — less than ₹1 a day

First get the union. If 20 like neither, then those liking at least one = 120 − 20 = 100. Now use n(A ∪ B) = n(A) + n(B) − n(A ∩ B): 100 = 70 + 60 − both, so both = 130 − 100 = 30. Cross-check the four regions: tea only = 70 − 30 = 40, coffee only = 60 − 30 = 30, both = 30, neither = 20, and 40 + 30 + 30 + 20 = 120, the whole group. Answering 130 − 120 = 10 means you forgot to remove the 20 who like neither before applying the formula.