Jawabanmu

2014-08-20T12:22:47+07:00
2014-08-20T12:33:55+07:00
4) a+b=b+a =  (3x-2)+(2x-4)= 5x-6
7)a+b=b+a= 3x+(2x+1)=5x+1
8)a+b=b+a = 5+(2x-4)=2x+1