binary form of the number obtained by adding 7 to -5 

 10010

  the msb is discarded,so four bit representation in binary form =

 0010

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  binary form of the number obtained by adding +5 to -5 

 10000

  the msb is discarded,so four bit representation in binary form =

 0000

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  binary form of the number obtained by adding +3 to -5 

 01110

  the msb is discarded,so four bit representation in binary form =

 1110

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