Question 958260
Set u = ones digit
 t = tens digit
t*10 + u >= 30
t*10 + u <= 60
u = t-3

Possible tens digits are 3 4 and 5, not 6 since 60 is not prime.
2 digit prime numbers beginning with 3
31 , 37 
2 digit prime numbers beginning with 4
41 , 43 , 47
2 digit prime numbers beginning with 5
51 , 53 , 57

41 is the only number that is prime between 30 and 60
and the tens digit is 3 more than the units digit.