1) х/72 - 13/72 = 29/72
х/72= 29/72+13/72
х/72= 42
х=42
2) (29/42 - а) - 13/42= 11/42
29/42-а=13/42+11/42
29/42-а=24/42
а=29/42-24/42
а=5/42
3) 15/17 - ( б - 3/17 ) = 6/17
б - 3/17 = 15/17 - 6/17
б - 3/17 = 9/17
б = 3/17 + 9/17
б = 12/17
4) 29/43 - ( м+ 13/43) = 5/43
м + 13/43 = 29/43 - 5/43
м + 13/43 = 24/43
м = 24/43 - 13/43
м = 11/43