`\text{2)}`
`\text{a)}`
`11 3/4 - ( 6 5/6 - 4 1/2 + 1 2/3)`
`= 11 3/4 - (41/6 - 9/2 + 5/3)`
`= 47/4 -4`
`=31/4`
`\text{b)}`
`(5 7/8 - 2 1/4 - 0,5 ) : 2 23/26`
`= (47/8 - 18/8 - 4/8 ) : 2 23/26`
`= 25/8 : 2 23/26`
`= 25/8 : 75/26`
`= 13/12`
`\text{c)}`
`(17 13/15 - 3 3/7) - (2 12/15 - 4)`
`= 17 13/15 - 3 3/7 - 2 12 /15 +4`
`= (17 13/15 - 2 12/15) + ( -3 3/7 +4 )`
`= 226/15 + 10/7`
`= 1732/105`
`\text{d)}`
`2 2/3 . {-4}/5 . 0,375 . (-10) . {-15}/24`
`= 8/3 . {-4}/5 . (-3,75) . {-15}/24`
`= (8/3 . {-4}/5) . (-3,75 . {-15}/24)`
`= -32/15 . 75/32`
`= -5`