Barisan artimatika suku ke-5=37 suku ke-8=19jumlah 60 suku

cari beda37 = a + 4b19 = a + 7b  -18 = -3b-18 = 3b-18 : 3 = b-6 = b
cari suku awalU5 = a + 4b37 = a + 4b37 = a + 4(-6)37 = a - 2437 + 24 = a61 = a
S60 = 60/2 [(2 x 61) + (60-1)-6]S60 = 30 [122 + (59 x -6)]S60 = 30 [122 + -354]S60 = 30 (-232) = -6960