Ответ:
Формула периметра: P = ( a + b ) * 2
1) ( a + b ) * 2 = 98
a + b = 98 : 2 = 49
a = 20, 24, 26, 27, 28, 30
b = 29, 25, 23, 22, 21, 19
2) ( a + b ) * 2 = 120
a + b = 120 : 2 = 60
a = 30, 35, 40, 50
b = 30, 25, 20, 10
3) ( a + b ) * 2 = 140
a + b = 140 : 2 = 70
a = 50, 40, 35, 55, 45
b = 20, 30, 35, 15, 25