tolong kerjakan dengan caranya nomor 5 bagian B

U1 = 5
U8 + U10 = 140

➡ a + 7b + a + 9b = 140
= 2a + 16 b = 140
= 2(5) + 16b = 140
= 10 + 16b = 140
= 16b = 130
= b = 130/16
b = 65/8

U12 = a + (n-1) b
U12 = 5 + (12-1) 65/8
U12 = 5 + 11(65/8)
U12 = 5 + 715/8
U12 = 5/1 + 715/8
U12 = 40/8 + 715/8
U12 = 755/8
U12 =94,375

Semoga membantu. Maaf kalau ada kesalahan