1/3х + 2/3х - 0,75 * 2/3х = 3/3х - 3/4 * 2/3х = х - 2/4х = 2/4х = 1/2х = 0,5х
1/2х при х = 7 0,5х при х = 7
1/2 * 7 = 7/2 = 3 1/2 0,5 * 7 = 3,5
102000-х=390
х=102000-390
х=101610
12-XII
13-XIII
15-XV
16-XVI
21-XXI
22-XXII
23-XXIII
51-LI
52-LII
36:2,3,4,6,9,12,18,36
48:2,3,4,6,8,12,16,24,48
общие делители:2,3,4,12.