Six years from now, the average of Monu's age that time and Ninu's age that time will be 29 years. Five years ago, if the ratio of Monu's age to the Ninu's age that time was 11:7, what is Ninu's present age ?

Monu : ninu
11x : 7x before 5 year
- : - present
29 avg of both after 6 year
Now we can write (11x+11)+(7x+11)/2=29
{It means avg of 11x and 7x equals to 29 but after 11 year(before 5 nd after 6 =(6+5=11))}
Now we solve it (11x+11)+(7x+11)/2=29
And we calculate x=2

So we write 11*2 : 7*2
22. : 14. Before 5 year
( 22+5) 27 : 19 (14+5) present

Let present age of Monu and Ninu are X and Y years respectively.
After six years of now, they have age as (X + 6) and (Y + 6) respectively.
Total age after 6 years = 2 * 29
X + 6 + Y + 6 = 58
X + Y = 46 ------------------------------------ (1)
5 years ago ratio of their age = 11 : 7
So, Let 5 years ago their age were 11n and 7n respectively.
Let total age 5 year ago = 11n + 7n = 18n.
(X -5) + (Y - 5) = 18n
X + Y - 10 = 18n
46 - 10 = 18n
n = 2
So,
5 years ago Ninu's age = 7n = 7 *2 = 14 years.
And Monu's age = 11n = 11 * 2 = 22 years.