Răspuns :
9 / 30 - 2 / 30 = 7 / 30
11 / 30 - 2 / 30 = 9 / 30 = 3 / 10
15 / 30 - 2 / 30 = 13 / 30
17 / 30 - 2 / 30 = 15 / 30 = 1 / 2
19 / 39 - 2 / 30 = 190 / 390 - 26 / 390 = 164 / 390 = 82 / 195
9 / 30 - 2 / 30 = 7 / 30
11 / 30 - 2 / 30 = 9 / 30 = 3 / 10
15 / 30 - 2 / 30 = 13 / 30
17 / 30 - 2 / 30 = 15 / 30 = 1 / 2
19 / 39 - 2 / 30 = 190 / 390 - 26 / 390 = 164 / 390 = 82 / 195