Among 250 viewers interviewed who watch at least one of the three TV channels namely A, BC. 116 watch A, 127 watch C, while 107 watch B. If 60 watch exactly two channels. How many watch exactly one channel?  Pick
A) 185 B) 180 C) 170 D) 190 E) 195
250 = n(Exactly 1 channel) + n(Exactly 2 channels) + n(Exactly 3 channels)   250 = n(Exactly 1 channel) + 60 + n(Exactly 3 channels)   Let's find the value of n(Exactly 3 channels) = x   250 = n(A) + n(B) + n(C) - n(A and B) - n(B and C) - n(C and A) + n(A and B and C)   Note that each of n(A and B) is the sum of 'number of people watching exactly two channels A and B' and 'number of people watching all three channels'.   250 = 116 + 127 + 107 - n(Exactly 2 channels) - 3x + x   250 = 116 + 127 + 107 - 60 - 2x   x = 25   250 = n(Exactly 1 channel) + 60 + 25   n(Exactly 1 channel) = 170   Answer (170)
<result>C</result>
Among 250 viewers interviewed who watch at least one of the three TV channels namely A, BC. 116 watch A, 127 watch C, while 107 watch B. If 60 watch exactly two channels. How many watch exactly one channel?