If a number has 5 as it's last digit, it's always divisible by 5: multiples of 5 have either 5 or 0 as the last digit.
If a number is divisible by 5, it is not a prime with one exception: of 5 itself. This is from the definition of prime numbers: divisible only by 1 and by itself.
Education is better than money because in order to get a good paying job you need to have a good level of education completed. If you drop out of highschool or just never completed it then you will never be able to get a high paying job without highschool level education.