In the first pair, the sum of the numbers inside the parentheses is 1 + 3 + 6 = 10.
The square of this sum is 102 = 100.
In the second pair, the sum of the numbers inside the parentheses is 2 + 3 + 5 = 10, and the square of this sum is also 102 = 100.
Conclusion: Thus, the correct answer is (A) 100.
Arun’s present age in years is 40% of Barun’s. In another few years, Arun’s age will be half of Barun’s. By what percentage will Barun’s age increase during this period?