what is the probability of choosing a same letter from the word “JOHNSON” and “JONES” ?

(first blank = letter selected from first word, 2nd blank =letter from 2nd word)

Out of the 7 letters in Johnson, 6 appear in Jones

Once we select the first letter, we can select only one letter from Jones, such that both are the same

\frac{6}{7} * \frac{1}{5} = \frac{6}{35}