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[tex]diketahui \: \: \\ a = 200 \\ b = 35 \\ ditanya \: S12 \\ ket.3tahun = \frac{36bulan}{3bulan} = 12 \\ jawab \\ Sn = \frac{n}{2}(2a + (n - 1)b) \\ S12 = \frac{12}{2} (2 \times 200 + (12 - 1)35) \\ S12= 6(400 + 385) \\ S12 = 6(785) \\ S12 = 4710 \: unit \: [/tex]

[tex]sn = \frac{n}{2} (2a(n - 1)b)[/tex]
n ada 12 because banyaknya
triwulan 12.
S12=12÷2(400+(12-1)35)
S12=6(785)
S12=4710