Question

4 years ago The average age of father and son is 27.5 Today the ratio of father to son is 5:16 What is the age of son now​

Answer 1

Answer:

4 years ago let the age of father and son be x and y respectively....

So....

$\frac{x + y}{2} = 27.5 \\ x + y = 55$

TODAY THE PRESENT AGE OF FATHER AND SON ARE x+4 and y +4.....

ratio of their ages today is 5:16....

NOW....

$\frac{x + 4}{y + 4} = \frac{5}{16}$

BY CROSS-MULTIPLICATION...

$16x + 64 = 5y + 20$

substitue the value of y=55-x

$16x + 64 = 5(55 - x) + 20 \\ 16x + 44 = 275 - 5x \\ 21x = 275 - 44 \\ x = \frac{231}{21} \\ x = 11$

SO PRESENT AGE OF SON = 15