` \frac{1,5}{9} . 2/7 + 5/9 . 5/7 - 8/3`

`= (1/6 . 2/7) + (5/9 . 5/7) - 8/3`

`= (1/21 + 25/63) - 8/3`

`= (3/63 + 25/36) - 8/3`

`= 4/9 - 8/3`

`= 4/9 - 24/9`

`= -20/9`

`-7/83+496.(-7/813)+(-7/813)+(-7/813) . 316`

`= -7/83 + 496 . (-7/813) - 7/813 - 7/813 . 316`

`= -7/813 . (1+ 496 + 1 + 316)`

`= -7/813 . 814`

`= -5698/813`

`-9/10 . 5/14 + 1/10 . (-9/2)+ 1/7 . (-9/16)`

`= (-9/10 . 5/14) + (1/10 . \frac{-9}{2}) + ( 1/7 .\frac{-9}{16})`

`= -9/28 - 9/20 - 9/112`

`= -180/560 - 252/560 - 45/560`

`= \frac{-180-252-45}{560}`

`= -477/560`

`(1999/2011-2011/16999)-(-12/1999-12/11)`

`= 1999/2011-2011/16999 + 12/1999 + 12/11`

`≈ 1,973`

`\color{#A0C4FF}{\text{~}}\color{#BDB2FF}{\text{安}}\color{#FFC6FF}{\text{宝}}\color{#FFADAD}{\text{~}}`