`a) 3/7 + 11/14 + 19/28`
`= 3/7 = 12/28 ; 11/14 = 22/28`
`= 12/28 + 22/28 + 19/28`
`= 34/28 +19/28`
`= 53/28`
`b) 2/5 + \frac{-1}{6} - 3/4 - \frac{-2}{3}`
`= (2/5 - 3/4) - 1/6 + 2/3`
`= 8/20 - 5/6`
`= \frac{-13}{30}`
`c) 1/3 + 3/8 - 7/12`
`1/3 + 3/8 - 7/12`
`= 17/24 - 7/12`
`= 1/8`
`d) 7/8 + 5/16 + \frac{-3}{4}`
`= 19/16 + \frac{-3}{4}`
`= 7/16`
`e) 4/13 + \frac{-11}{5} + 9/13 + 6/5`
`= (4/13+9/13)+(\frac{-11}{5}+6/5)\frac{-3}{4}`
`= 0-\frac{3}{4}`
`= \frac{-3}{4}`
`f) 1/4-2/3-11/18`
`= 9/36 - 24/36 - 22/36`
`= \frac{-5}{12} - 11/18`
`= \frac{-37}{36}`
`g) \frac{-15}{4}+\frac{-6}{14}+15/4`
`= \frac{-15}{4} + 15/4`
`= 0/4 = 0`
`= 0 -6/17`
`= \frac{-6}{17}`
`h) 5/11 + 16/22 + \frac{-12}{4} + \frac{-2}{11}`
`= (5/11 - 2/11) + 16/22 - 12/4`
`= 3/11 + 16/22`
`= \frac{-12}{4}`
`= 1-3 = -2`
`i) 7/9 + 5/12 - 3/4`
`= 5/12 -3/4`
`= \frac{-1}{3}`
`= \frac{-1}{3} + 7/9 - 4/3`
`= 4/9`
