Second is the working place of the first.

First control the flow /movement of the second.

8 : 12 = (8 x 2 - 4) :: 6 : (6 x 2 - 4) = 8

Apple = 1 + 16 + 16 + 12 + 5 = 50
Orange = 15 + 18 + 1 + 14 + 7 + 5 = 60

Grenade and gun are fire arms whereas head and brain are body organs.

The relationship is x : (x² - 9).

Cobbler works with leather and tailor works with cloth.

Haematology is the study of Blood. Similarly, Phycology is the study of Algae.`

Groups of Lions are called Pride, Similarly, Group of cats are called Clowder.

2⁵ = 32,
Similarly, 3⁵ = 243