Jawabanmu

2014-09-05T20:20:25+07:00
(5x -6y +8z) + (7x -9z) - (2y + 9z - 10)
5x + 7x - 6y - 2y + 8z - 9z -9z + 10
=12x-8y-10z+10

2014-09-05T22:25:22+07:00
(5x - 6y + 8z) + (7x - 9z) - (2y + 9z - 10)
= 5x - 6y + 8z + 7x - 9z - 2y - 9z + 10
= 5x + 7x - 6y - 2y + 8z - 9z - 9z + 10
= 12x - 8y - 10z + 10