Solution:The logic here is :(125, 91) β (5Β³, 5 Γ (5 + 1) Γ 3 + 1)
(64, 61) β (4Β³, 4 Γ (4 + 1) Γ 3 + 1)
(27, 37) β (3Β³, 3 Γ (3 + 1) Γ 3 + 1)
But,
(8, 20) β (2Β³, 2 Γ (2 + 1) Γ 3 + 1) β (8, 19) β (8, 20)
Hence, (8, 20) is the correct answer.