Выражение 1)2/3a•7/12b= 2)8/9x•1 4/5y= 3)5m•2 6/11n•2 5/14k=

1)2/3a*7/12b=7/18
2)8/9x*1 4/5y=8/9x*9/5y=8/5xy=1 3/5xy
3)5m*2 6/11n*2 5/14k=5m*28/11n*33/14k=5m*6nk=30mnk

1) 2/3а * 7/12b = 7/18ab

2) 8/9x * 1 4/5y =
(1 4/5y = 9/5y)
8/9x * 9/5y = 8/5xy = 1 3/5xy

3) 5m * 2 6/11n * 2 5/14k =
(2 6/11n = 27/11n)
(2 5/14k = 33/14k)
5m * 28/11n * 33/14k = 30m/nk