Aptitude Hack#77(11-5-19)

Question:

One year ago, the ratio of Gaurav's and Aditya’s age was 6: 7 respectively. Four years hence, this ratio would become 7: 8. How old is Aditya?

   A )   36 years
   B )   37 years
   C )   38 years
   D )   39 years

Answer: A) 36 years

Explanation:

Let Gaurav's and Aditya's ages 
one year ago be 6x and 7x years respectively.

Then, gaurav’s age 4 years hence
 = (6x + 1) + 4 = (6x + 5) years.

Aditya’s age 4 years hence
 = (7x + 1) + 4 = (7x + 5) years.

=> (6x+5)/ (7x+5) = 7/8 

=> 8(6x+5) = 7 (7x + 5)  

=> 48x + 40 = 49x + 35  

=> x = 5.

Hence, Aditya’s present age = (7x + 1) = 36 years.