Question 431284
Without loss of generality, assume only positive integers.  There are 90 2-digit positive integers, while there are 13 2-digit positive integers divisible by 7.

Hence the probability is 13/90.

Why 13 2-digit positive integers divisible by 7?

98 = 14 + (n-1)7, from the arithmetic sequence formula.
==> 84 = (n-1)7
==> 12 = n-1
==> n = 13.