` \color{#0074D9}{#n}\color{#0088DD}{q}\color{#3399FF}{o}\color{#66AAFF}{c}\color{#99CCFF}{c} `

`a) 3/13 . 6/11 + 9/13 . 3/11 - 3/13 . 4/11 `

`= 3/13 . (6/11 - 4/11) + 9/13 . 3/11 `

`= 3/13 . 2/11 + 9/13 . 3/11 `

`= 6/143 + 27/143 `

`= 3/13 `

`b) 1,4 . 15/49 - (4/5 + 2/3) + 2 1/5 `

`= 7/5 . 15/49 - 4/5 - 2/3 + 11/5 `

`= 7/5 . 15/49 - (4/5 - 11/5) - 2/3 `

`= 7/5 . 15/49 + 7/5 - 2/3 `

`= 7/5 . (15/49 + 1) - 2/3 `

`= 7/5 . 64/49 - 2/3 `

`= 64/35 - 2/3 `

`= 122/105 `