Jawabanmu

2014-08-14T23:25:28+07:00
(9a+12)-(7a+14)= 9a-7a+12-14 = 2a-2
2014-08-15T00:21:46+07:00
( 9a + 12 ) - ( 7a +14 )
= ( 9a +12 ) - ( 7a -14 )
= 9a -7a +12 -14
= 2a -2