Assistant (BS-16) Land Record Authority 2020

Explanation:

Let numbers be x and y 

According to given condition

           x + y = 67 …..(i)

           x – y = 3   …..(ii) 

Adding (i) and (ii) 

                2x = 70 

                   x = 35 

Puting value of x in equation (i)

           35 + y = 67 

                   y = 32

So numbers are 35 and 32

Four years ago, average age of A,B,C 

[(A-4) + (B-4) + (C-4)]/3 =25

               A + B + C  -12 = 75

                      A + B + C = 87 ….(I) 

Five yeas ago, average of B and C 

          [(B-5) + (C – 5)]/2 = 20

                    B + C – 10 = 40 

                         B + C = 50 ……(ii) 

Solving (i) and (ii) 

                                A =37 years

3 : x :: 12 : 20

3/x = 12/20

      x = (3 x20)/12

      x =  5

Five years ago ages of A and B are A – 5 , B – 5

So Averge ,  (A + B)/ 2 = 15

                     [(A – 5) + (B – 5)]/2 = 15

                      A + B – 10 = 30 

                      A + B = 40 ……….(i) 

Now average ages of A , B and C is 20 

                    ( A + B + C)/3 = 20 

                      A + B + C = 60 ……… (ii) 

Putting equation (i) into (ii) 

                           40 + C = 60 

                                    C = 20

After 10 years  C = 20 + 10 = 30