Explanation:

To solve this, break it down step-by-step:

- Calculate 35% of 500:

- 0.35 * 500 = 175

- Calculate 55% of 600:

- 0.55 * 600 = 330

- Add the two results:

- 175 + 330 = 505

- Calculate 26% of 800:

- 0.26 * 800 = 208

- Set up the equation:

- 505 = ? + 208

- Solve for '?':

- ? = 505 - 208 = 297

- Option 1: 306

- Incorrect, 505 - 208 is not 306

- Option 2: 310

- Incorrect, 505 - 208 is not 310

- Option 3: 297

- Correct, 505 - 208 equals 297

- Option 4: 300

- Incorrect, 505 - 208 is not 300

- Option 5: 295

- Incorrect, 505 - 208 is not 295

Since the correct calculation leads to 297, Option 3 is the right answer.