Jawabanmu

2014-02-09T18:15:26+07:00
12+3a=5+2a
: 12+3a-2a=5+2a-2a
: 12+a=5
:a=5-12
a=-7
1 5 1
2014-02-09T18:15:40+07:00
12 + 3a = 5 + 2a
3a - 2a = 5-12
a = -7
1 5 1