\(287-\left(-12\right)-\left(87-129\right)\)
\(=287+12-87+129\)
\(=\left(287-87\right)+\left(12+129\right)=200+141=341\)
`287-(-12)-(87-129)`
`=287 + 12 -87+129`
`= (287-87) + (12+129)`
`= 200+ 141`
`=341`
\(287-\left(-12\right)-\left(87-129\right)\\ =287+12-87+129\\ =\left[287+\left(-87\right)\right]+\left(129+12\right)\\ =200+141\\ =341\)
\(287-\left(-12\right)-\left(87-129\right)\\ =287+12-87+129\\ =\left(287-87\right)+\left(12+129\right)\\ =200+141\\ =341\)