correct answer is: a) 56 years

Explanation

Here,
The ratio of the ages of Manasbabu and Dipakbabu is 7\;:\;9.
And, the age of Dipakbabu be 72 years.
Let, the age of Manasbabu be ‘x’ years.
According to the question,
7\;:\;9\;=\;x\;:\;72
\rightarrow\large\frac{7}{9}\normalsize=\large\frac{x}{72}
\rightarrow 9x=\left(7\times72\right)
\rightarrow x=\large\left(\frac{7\times72}{9}\right)
\rightarrow x=56
So that, the age of Manasbabu be 56 years.
Ans: 56 years.

Another method to articulate this particular math query is available:

1. Manasbabu and Dipakbabu have an age ratio of 7:9. If Dipakbabu is 72 years old, what is Manasbabu’s age?
2. Given that Dipakbabu’s age is 72 years and the ratio of their ages is 7:9, what is Manasbabu’s age?
3. When Dipakbabu’s age is 72 years and the ratio of their ages is 7:9, what is Manasbabu’s age?