Jawabanmu

2017-02-18T00:16:04+07:00
Diketahui :
a + a + 3b = 23
a + 2b + a + 6b = 38

Ditanya : S30

Jawab :
2a + 8b = 38
2a + 3b = 23
------------------- (-)
5b = 15
b = 3

2a + 9 = 23
2a = 14
a = 7

S30 = 15(2a + 29b) = 15 ( 14 + 87 ) = 15 (101) = 1.515