The ratio of a man's age to his father's age is 4 : 5, and the ratio of his age to his son's age is 6 : 1. Four years ago these ratios were 11 : 14 and 11 : 1, respectively. The ratio of the age of the grandfather to that of the grandson 12 years from now will be:

A. 12 : 5

B. 14 : 3

C. 18 : 5

D. 18 : 7

Answer: Option C

Solution(By Examveda Team)

$$\eqalign{ & 1{\text{ unit}} \to 4{\text{ years}} \cr & {\text{So current age}} \cr & {\text{Man}}:{\text{Father}}:{\text{Son}} \cr & \,\,\,{\text{48}}\,\,\,\,\,\,\,\,\,\,\,\,\,{\text{60}}\,\,\,\,\,\,\,\,\,\,\,\,\,{\text{8}} \cr & {\text{Required answer}} = \frac{{60 + 12}}{{8 + 12}} \cr & = \frac{{72}}{{20}} \cr & = \frac{{18}}{5}{\text{ or }}18:5 \cr} $$