Let Shreya's present age be x years. Since Arjun is twice as old as Shreya, Arjun's age is 2x years.
According to the problem, five years ago, Arjun's age was three times Shreya's age. This can be expressed as:
2x - 5 = 3(x - 5).
Solving this equation:
2x - 5 = 3x - 15
Rearrange the terms to find x:
2x - 3x = -15 + 5
-x = -10
Thus, x = 10.
This means Shreya is 10 years old, and Arjun, being twice as old, is 2 * 10 = 20 years old.
The sum of their present ages is 10 + 20 = 30 years.
Therefore, the sum of their present ages is 30 years.
Let $\Sigma = \{a, b, c\}$. For $x \in \Sigma^*$, and $\alpha \in \Sigma$, let $\#\alpha(x)$ denote the number of occurrences of $\alpha$ in $x$. Which one or more of the following option(s) define(s) regular language(s)?