Question 432174

Let age of younger boy =x

age of older boy = y

x+y = 18 ..........(1)

and 3y - 4x = 12 .........(2)


multiply equation 1 by 4 and add both equations

4x + 4y = 72

3y - 4x= 12

then 7y = 84  

=> y = 84/7 = 12

x = 18 -12 = 6

age of younger boy is 6, age of older boy is 12.