First see what 4 could go by and the answer closest to 18 that is not more than the answer is the first number of the answer.
4×1=4
4×2=8
4×3=12
4×4=16
In this case 4 is the first number of the answer because if you fo 4 by 5 it equals 20 , which is more than the answer
4×5=20
after that , you subtract the answer, 18 minus 16 which is 2 because nothing times 4 equals 2
So the remainder is 2/4 or .50
If you have any questions about this please don't hesitate to ask me