Respostas

2013-07-29T15:18:38-03:00
10x-2x=21+3+9 
8x=33
x=33/8
x=4,125 
1 5 1
2013-07-29T15:35:50-03:00
10x+9=21+2x+3
10x-2x=21+3+9
8x=24+9
8x=33
x=33/8
x=4,125
1 5 1