Fatin Banyu Putih X-F, Absen 9 Nomor 9 9. Dik= a= 1500, b= 500 Dit= S18, deret aritmatika Jawab= Sn= 1/2n [a + (n-1) b] S18= 1/2 . 18 [ 1500 + (18-1) 500] S18= 9 [ 1500 + 17 . 500 ] S18= 9 [ 1500 + 8500 ] S18= 9 . 10000 S18= 90000 Dr. Hj. Lizza Novrida M.pd (Matematika)