What approximate value will come in place of '?' if (?)2 items are removed from a container of 4.023 items, leaving 27.99 items?

What approximate value will come in place of the question mark (?) in the following question? (Note: You are not expected to calculate the exact value.)24.89% of ? + 75.15% of 399.78 = 16 of 2499.68%

What approximate value will come in place of the question mark (?) in the following question? (13.13)2 + (15.89)2 - (12.12)2 ÷ 9.09 = ?