Explanation:

- First, simplify the base expressions: (6.99)² ˜ 49 and (12.99)² ˜ 169.

- The equation is then simplified as: 48.99 × ?342.81 ÷ 49 + 169 = x.

- Simplify 342.81 ÷ 49, which approximately equals 7.

- The equation now reads: 48.99 × 7 + 169 = x.

- Further simplify 48.99 × 7 ˜ 343.

- Now, 343 + 169 = 512.

- Among the given options, none of them exactly match 512.

So, none of the options provided match the derived value from the calculations. It seems there might be a misunderstanding or miscalculation in any initial conditions.