1.скопка1\5*3\4скопка*2\3 2. 2\9*скопка3\10*7\8скопка 3.15\19*скопка19\25*7\9скопка*5\7 4.скопка10\13*11\12скопка*скопка12\55*13\20скопка

1. (1/5×3/4)×2/3=3/20×2/3=1/10=10

2.2/9×(3/10×7/8)=2/9×21/80=1/3×7/40=7/120

3.15/19×(19/25×7/9)×5/7=15/19×133/225×5/7=15/19×19/45=

=1/3

4.(10/13×11/12)×(12/55×13/20)=55/78×78/550=1/10