Ответы и объяснения

2014-02-06T20:27:11+04:00
1) x/72 - 13/72 = 29/72
x -13 = 29
x = 42
2) (29/42 -a) - 13/42 = 11/42
-a + 16/42 = 11/42
-a = -5/42
a = 5/42