B) 2x + (-416) - (231 - 416 )
= 2x - 416 - 231 + 416
= 2x - ( 416 +231 - 416 )
= 2x - 231
D) 211-(123-x)+(123-211)
= 211 - 123 + x + 123 - 211
= ( 211 - 123 +123 - 211 )+ x
= 0+ x
= x
b) 2x + (-461) - (231 - 416)
= 2x - 461 - (231 - 416)
= 2x - 461 + 185
= 2x - 276
d) 211 - (123 - x) + (123 - 211)
= 211 - 123 + x + 123 - 211
= (211 - 211) + (-123 + 123) + x
= 0 + 0 + x
= x