Nomor 7, 8, 9 yaaa pliss besok udah dikumpulin soalnya

untuk no. 8

a = U1 = 120.000
U2 = 125.000
b = 125.000-120.000 = 5.000
n = 12

S12 = n/2 . 2a + (n-1) b
S12 = 12/2 . 2.120.000 + (12-1) 5.000
S12 = 6 . 240.000 + 11 . 5.000
S12 = 6 . 240.000 + 55.000
S12 = 6. 295.000
S12 = 1.770.000

B. Rp. 1.770.000