pada suatu deret aritmatika diketahui U5=31 Dan U10=69 Nilai U15 adalah. ...... a. 96 b. 101 c. 107 d. 112

b = (69-31)/(10-5) = 38/5
U5 = a + 4b
31 = a + (4x38/5)
(31x5)/5 = a + 152/5
a = (155-152)/5 = 3/5

U15 = 3/5 + (14x38/5)
U15 = (3+532)/5
U15 = 535/5 = 107

jawaban : c