Question

Three years ago the average age of A and B was 18 uears with C joining them, the average age becomes 22 years. How old is C now? ​

Answer 1

Answer:

C is 33 years old now.

Step-by-step explanation:

Let The current age of A be X yrs.

Age of B be Y yrs

According to the question;

Three years ago,

Average ( A , B ) = ( X - 3 + Y - 3 )/2

18 = ( X + Y - 6 ) /2

or, 36 = X + Y - 6

so, X + Y = 42__________________(1)

Now C joined , Let age of C be Z

Three years ago,

Average ( A, B , C ) = ( X - 3 + Y - 3 + Z - 3 )/3

22 = ( X + Y + Z - 9 ) /3

or, 66 = X + Y + Z - 9

or, X + Y + Z = 75

or, Z = 75 - ( X + Y )

Putting the value of X + Y from (1)

We get, Z = 75 - 42 = 33

So, the present age of C is 33 years.

Answer 2

Answer:

C is 33 years old now.

Step-by-step explanation:

Let The current age of A be X yrs.

Age of B be Y yrs  

According to the question;  

Three years ago,  

Average ( A , B ) = ( X - 3 + Y - 3 )/2  

18 = ( X + Y - 6 ) /2  

or, 36 = X + Y - 6  

so, X + Y = 42__________________(1)  

Now C joined , Let age of C be Z  

Three years ago,  

Average ( A, B , C ) = ( X - 3 + Y - 3 + Z - 3 )/3

22 = ( X + Y + Z - 9 ) /3  

or, 66 = X + Y + Z - 9

or, X + Y + Z = 75  

or, Z = 75 - ( X + Y )  

Putting the value of X + Y from (1)

We get, Z = 75 - 42 = 33

So, the present age of C is 33 years.