1 , (a-b+c)-(a+c) =a-b+c-a-c=(a-a)+(c-c)-b =-b (dpcm)
2 ,(a+b)-(b-a)+c =a+b-b+a+c=(a+a)+(b-b)+c=2a+c (dpcm)
3 , -(a+b-c)+(a-b-c) =-a-b+c+a-b-c=(-a+a)+(-b-b)+(c-c) =-2b (dpcm )
4 ,a(b+c)-a(b+d) =ab+ac-ab-ad =a(b+c-b-d)=a(c-d)(dpcm)
5, a(b-c)+a(d+c) =ab-ac+ad+ac =a(b-c+d+c) =a(b+d)(dpcm)