Respuestas

2013-06-10T21:48:34+02:00
21+3(2x-2)-2x=60-x
21+6x-6-2x=60-x
15+4x=60-x
4x+x=60-15
5x=45
x=9

Verificando

21+3(2x-2)-2x=60-x   -->x=9

21+3(2(9)-2)-2(9)=60-9
21+3(18-2)-18=51
21+3(16)-18=51
21+48-18=51
69-18=51
51=51


2013-06-10T22:15:49+02:00
21+6x -6-2x=60-x
6x-2x+x=60-21+6
5x=45
x=9
verificacion
21+3[2(9)-2]-2(9)=60-(9)
21+3(18-2)-18=60-9
21+3(16)-18=51
21+48-18=51
51=51