Пошаговое объяснение:
1) (2/7 +3 1/2)·4 2/3=(4/14 +3 7/14)·14/3=3 11/14 ·14/3=53/14 ·14/3=53/3=17 2/3
2) (2 1/5 -2 3/4)·2 2/19=(2 4/20 -2 15/20)·40/19=-11/20 ·40/19=(-11·2)/19=-22/19=-1 3/19
3) (5 6/7 +3 5/21)·2 1/10=(5 18/21 +3 5/21)·21/10=8 23/21 ·21/10=191/21 ·21/10=191/10=19,1
4) (7 5/12 -3 1/6)·2 2/17=(7 5/12 -3 2/12)·36/17=4 3/12 ·36/17=4 1/4 ·36/17=17/4 ·36/17=9
