`1) ( (-5)/11 ) . 7/15 . ( 11/(-5) ) . ( -30 )`

`= [( (-5)/11 ) . ( 11/(-5) )] . [ 7/15 . ( -30 )]`

`= 1 . ( -14 )`

`= -14`

$\\$

`2) (-7)/15 . 5/8 . 15/(-7) . ( -32 )`

`= ( (-7)/15 . 15/(-7) ) . [ 5/8 . ( -32 )]`

`= 1 . ( -20 )`

`= -20`

$\\$

`3) -2 . (-32)/21 . (-7)/4 . (-3)/8`

`= 64/21 . (-7)/4 . (-3)/8`

`= -16/3 . (-3)/8`

`= 2`

$\\$

`4) 2 3/11 . 1 1/12 . ( -2,2 )`

`= 25/11 . 13/12 . ( -11/5 )`

`= 325/132 . ( -11/5 )`

`= -65/12`

$\\$

`5) 1 1/17 . 1 1/24 . ( -5,1 )`

`= 18/17 . 25/24 . ( -51/10 )`

`= 75/68 . ( -51/10 )`

`= -45/8`

$\\$

`6) ( (-13)/25 ) . 5/32 . ( 25/(-13) ) . ( -64 )`

`= [( (-13)/25 ) . ( 25/(-13) )] . [ 5/32 . ( -64 )]`

`= 1 . ( -10 )`

`= -10`