`A = -3/4 + \frac{-1}{5} + \frac{-2}{3}`
`=-45/60 - 12/60 - 40/60`
`= \frac{-45-12-40}{60}`
`= -97/60`
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`B = -25/13 + \frac{-9}{17} + 12/13 + \frac{-25}{17}`
`= ( -25/13 + 12/13) + (\frac{-9}{17} +\frac{-25}{17})`
`= -1 + -2`
`= -3`