Bonsoir,
1)
30 issues
2)
a: 1/30
b: 2,4,6,8,10,12,14,16,18,20,22,24,26,28,30
15/30 = 1/2
c:5,10,15,20,25,30
6/30 = 1/5
d: 7,14,21
3/30 = 1/10
