1- 7a-9b+6a-4b= 14a-13b
7a+6a=14a
-9b-4b=-13b
2- a+b-c-b-c+2c-a= -2c-2b
a-a= -2a
b-b= -2b
c-c=-2c+2c=0
3- 5x-11y-9+20x-1-y= 25x-12y-10
5x+20x=25x
11y-y=-12y
-9-1=-10
4- -6m+8n+5-m-n-6m-11= -13m+9n-6
-6m-m-6m=-13m
8n-n=9n
+5-11=-6
5- -a+b+2b-2c+3a+2c-3b= +2a
-a+3a=2a
b+2b=3b-3b=0
-2c+2c=0
6- -81x+19y-30z+6y+80x+x-25y= -30z
+80x+x=81x-81x=0
+19y+6y=25y-25y=0..
7- 15a2-6ab-8a2+20-5ab-31+a2-ab= 8a2-12ab-11
15a2+a2=16a2-8a2=8a2
-6ab-5ab-ab=12ab
+20-31=-11
8- -3a+4b-6a+81b-114b+31a-a-b= +21a-30b
-3a-6a-a=-10a+31a=+21a
+4b+81b=85b-115b=-30b-114b-b=115b
9- -71a3b-84a4b2+50a3b+84a4b2-45a3b+18a3b= -48a3b
-71a3b-45a3b=-116a3b+68a3b=-48a3b
+50a3b+18a3b=68a3b+-84a4b2+84a4b2=0
10- -a+b-c+8+2a+2b-19-2c-3a-3-3b+3c= -2a-14
-a-3a=-4a+2a=-2a
+b+2b=-3b+3b=0
-c-2c=-3c+3c=0
-19-3=-22+8=-14
saludos ;)
