To get this, subtract 3 from 18 minus 1 (since greater than 3, less than 18)
18 - 3 = 15.
Since even numbers are divisible by 2, the answer should be divided by 2.
15/2 = 7 (7.5 actually, but decimals aren't considered here)
So therefore there is 7 even numbers greater than 3 and less than 18.
These are:
4, 6, 8, 10, 12, 14, 16
