Jawab:
(d.)  95, 87, 85

Penjelasan dengan langkah-langkah:
Diketahui data sebelumnya:
Rata-rata (m) = 85,5
Jumlah siswa (f) = 18

Cari jumlah nilai (n)
n = m×f
n = 85,5×18
n = 1.539

Nilai rata-rata baru (mb) = 86
fb = f + 3 = 18+3 = 21
Jumlah siswa baru (fb) = 21

D = Nilai Dayu
E = Nilai Edo
U = Nilai Udin

[Jumlah nilai baru]
n       + D + E + U   = mb × fb
1.539 + D + E + U  = 86×21
1.539 + D + E + U  = 1.806
maka, . . .
D + E + U = 1.806 - 1.539
D + E + U = 267

D = E + 8, maka E = D - 8
U = E - 2, maka U = (D-8)-2, U = D-10

Masukkin ke yg barusan
D + E + U = 267
D + (D-8) + (D-10) = 267
3D - 18 = 267
3D = 267 + 18
3D = 285
D = 285/3
D = 95
Nilai Dayu = 95

Cari nilai Edo (E)
E = D - 8, maka
E = 95 - 8
E = 87
Nilai Edo = 87

Cari nilai Udin (U)
U = E - 2
U = 87 - 2
U = 85
Nilai Udin = 85

Nilai Dayu, Edo, Udin
= 95, 87, 85 (opsi d.)

(xcvi)