Question

The average of 3 brothers is 15 yrs. If the age of two brothers is 15 yrs and 12 yrs, find the age of the third brother. ​

Answer 1

Let the total age of brother be y

Let the age of 3rd brother be x

ATQ

15=y/3

y=45years

Total age = 45years

15 +12+x=45

27+x=45

x=18years

Age of third brother is 18 years

Answer 2

Let x be the age of third brother

15+12+x/3 = 15

27+x/3 = 15

27+x = 45

x = 45-27

x = 18.