Final answer:
Riya's present age, represented by x, plus her age in 10 years (x + 10) equals 20 years. Solving the equation 2x + 10 = 20 results in x = 5, concluding that Riya's present age is 5 years.
Step-by-step explanation:
The question is about finding Riya's current age if the sum of her present age and her age after 10 years equals 20 years.
We are given the present age of Riya as x years. Therefore, her age after 10 years would be x + 10 years. The question essentially asks us to solve the following equation: x (present age) + (x + 10) (age after 10 years) = 20 years.
If we set up the equation based on this information, it would look like this:
x + (x + 10) = 20
Solving the equation:
2x + 10 = 20
2x = 20 - 10
2x = 10
x = 5
Riya's present age is 5 years. So, the correct answer to this question would be option a, which is x + 10.