Jawabanmu

2014-06-15T01:27:39+07:00
Kalau ada tiga deret aritmatika berurut, misal a, b, c. maka 2b = a + c

a + b + c / b - 6 = 9
2b + b /b - 6 = 9
3b / b-6 = 9
9b - 54 = 3b
6b = 54
b = 9