Iam a number between 60 and 100 . my ones digt is two less then my ten's digit .i am a prime number between

Here are the two digit numbers between 60 and 100 that have a units digit two less than the tens digit:
64
75
86
97

Of that list, we can see that
64 is composite since 64 has factors other than 1 and itself (eg: 2)
75 is composite since 75 = 3*25
86 is composite since 86 = 2*43
97 is prime. The only factors are 1 and itself

So if you're looking for a prime number that fits the criteria that it must be between 60 and 100, with the units digit two less than the tens digit, then the answer is 97