Răspuns:
Explicație pas cu pas:
77 - a> 20
a < 77 - 20
a < 57
____________
36 < 45 - a <39
36 < 45 - a
a < 45 - 36
a < 9
45 - a <39
a > 45 - 39
a > 6
Solutia 6 < a < 9
______________
a + 23 < 29
a < 29 - 23
a < 6
____________
18 < a - 25 < 29
18 < a - 25
a > 18 + 25
a > 43
a - 25 < 29
a < 25 + 29
a < 54
Solutia 43 < a < 54