Soln for the problem given is

n(a)=33 represents ( persons drink tea)

n(aUb)=52 represents( total persons)

n(a-b)=16 represents persons drink tea not coffee

n(a^b)=n(a)-n(a-b) {^ represents inverse of Union i.e intersection, mean drinks both coffee & tea)

=33-16

n(aUb)= n(a-b) + n (a^b) + n (b-a)

=> n(b-a)= 52-16-17

=19

its ( 19) by mistake i typed it 90 (sorry everyone)

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though i knw how to solve with these formulas but i tried to solve with matrix but could find soln.

anyway guys above is soln

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Rahul