Решите . 1) 7/15+4/9-3/10= 2) 5целых 7/9 - 3целых 5/6= 3) 13/21-(х-2целых 5/7) = 3/14

1) 7/15+4/9-3/10=72/90+40/90-27/90=85/90=17/18
2) 5    7/9 - 3  5/6= 52/9-23/6=104/18- 69/18= 35/18=1  17/18
3) 13/21-(х-2целых 5/7) = 3/14
х-2  5/7=13/21-3/14
х-19/7=26/42-9/42
х-19/7=17/42
х=17/42+19/7
х=17/42+114/42
х=131/42
х=3  5/42