Jawabanmu

2014-09-11T15:33:23+07:00
15a + 7b - 5c + (-11a - 12b + 13d)
= 15a-11a+7b-12b-5c+13d
= 4a - 5b - 5c + 13d
2 3 2
2014-09-11T15:33:49+07:00
15a+7b-5c dengan -11a-12b+13b
{15a+(-11a)}+{7b-12b}-5c+13d
4a-5b-5c+13d
2 4 2