15 - 15, 5, 3, 1
11 - 11, 1
68 - 68, 34, 17, 4, 2, 1
80 - 80, 40, 20, 16, 10, 8, 4, 2, 1
А) 14, 21, 28, 35, 42.
б) 12,15, 18, 21, 24, 27, 30, 33, 36, 39, 42.
в) 18, 27, 36.
г) 15, 20, 25, 30, 35, 40.
д) 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43
<em>(х+15)-8=17
х+15=17+8
х+15=25
х=25-15
х=10
(10+15)-8=17
25-8=15
15=15</em>