Q6 in the pic explain the meaning of the question in detail and answer it on paper as answer written by phone don't use proper mathematical operations

Dear Student,
Letter can be put in an envelope in 3! ways = 3 x 2 x 1 = 6 ways
Let we have 3 envelopes and 3 letter
Number of ways in which we can put 1 letter into the correct envelope = 3 (as we need to choose which letter we want o put in the correct envelope among the 3)
If we put 2 letters in the correct envelope then the third one automatically goes into the correct one, number of ways of doing that  = 1
Probability that atleast 1 letter is in the correct envelope = $\frac{3+1}{6} = \frac{4}{6} = \frac{2}{3}$

Regards,