а) (-3/7 5/13) - (4/7 5/13)= (-15/91) - (20/91)= - 35/91
б) 3/5 7/9 - 3/5 (7/9 - 5/6)= 21/45 - 3/5 (14/18 - 15/18)= 7/15 - 3/5 (-1/18)= 7/15 + 1/30= (14/30) + (1/30)= 15/30= 1/2
Ответ:а) -35/91б) 1/2
а) (-3/7 5/13) - (4/7 5/13)
= (-15/91) - (20/91)
= - 35/91
б) 3/5 7/9 - 3/5 (7/9 - 5/6)
= 21/45 - 3/5 (14/18 - 15/18)
= 7/15 - 3/5 (-1/18)
= 7/15 + 1/30
= (14/30) + (1/30)
= 15/30
= 1/2
Ответ:
а) -35/91
б) 1/2