Question

Aarav is 3 years younger than his sister keya. if the sum of their ages is 27 years, what are the present ages?

Answer 1

Let, Age of Aarav=X

So, Age of Keya=(X+3)

Sum of their ages,

X+(X+3)=27

2X+3=27

2X=24

X=12, Age of Aarav

(X+3), 12+3=15, Age of Keya.

Did you understand or not??

Answer 2

let the age of aarav be x
and age of keya be y

according to the given condition 

x =  y-3
or
x-y+3 = 0  ....... (i)

also we have

x + y = 27
or
x + y - 27 = 0   .............(ii)

from (i) and (ii) we have

x - y + 3 = 0
x + y - 27 = 0

by using elimination method

     x - y + 3 = 0
-    x + y - 27 = 0
-----------------------------
         -2y + 30 = 0

-2y = -30

y  = -30/-2

y = 15

thus the age of keya is 15 and the age of aarav is

15 - 3 = 12  thus age of aarav is 13 years