Jawabanmu

2014-09-10T19:17:34+07:00
(15a+7b-5c) - (-11a-12b+13c) =
15a + 7b - 5c + 11a + 12b - 13c =
15a + 11a +7b + 12b - 5c - 13c =
26a + 19b - 18c
2014-09-10T19:19:25+07:00
( 15a+7b-5c ) - ( -11a-12b+13c ) = 17abc - (-10)abc = 7