`6A`
`a, (3/8 + (-3)/4 + 7/12) : 5/6 + 1/2`
`= (9/24 + (-18)/24 + 14/24) . 6/5 + 1/2`
`= 5/24 . 6/5 + 1/2`
`= 1/4 + 1/2`
`= 1/4 + 2/4 = 3/4`
`b, 6 5/12 : 2 3/4 + 11 1/4 (1/3-1/5)`
`= 77/12 : 11/4 + 45/4(5/15 - 3/15)`
`= 77/12 . 4/11 + 45/4 . 2/15`
`= 7/3 + 3/2`
`= 14/6 + 9/6 = 23/6`
`c, 1 13/15 . 0,75 - (11/20 + 25%) : 7/5`
`= 28/15 . 0,75 - (11/20 + 1/4) . 5/7`
`= 7/5 - (11/20 + 5/20) . 5/7`
`= 7/5 - 4/5 . 5/7`
`= 7/5 - 4/7`
`= 49/35 - 20/35 = 29/35`
`d, ((-1)/2)^3 : 1 3/8 - 25%(-6 2/11)`
`= (-1)/8 : 11/8 - 1/4 . (-68)/11`
`= (-1)/8 . 8/11 + 17/11`
`= (-1)/11 + 17/11 = 16/11`
