1  ***
2013-11-12 pm 4:31:00
68.--.121.99
5x-6-3x=4x+6-(5x-6)
2x-6=4x+6-5x+6
2x-6=-x+12
2x+x=12+6=18
3x=18 therefore x=6
arithemetic sequence is key point. you shoule know the definition of this sequnce.

2  ***
2013-11-12 pm 4:34:00
68.--.244.244
1번님,사랑해요!!!감사해요!!!
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