13. 1,6
18. -15,12
19. -7, 1/2
40,44,48,52,56,60,64,68,72,76,80.........
I think it’s International Classification of Diseases but I’m not sure cause it doesn’t match anything with math good luck though.
About 15 because 9 times 5 = 45 reminder 3 than you add 3 times 5 = 15