Explanation:

Let's break it down:

- Calculate 30% of 6600.342:

$$ 0.3 \times 6600.342 = 1980.1026 $$

- Add and subtract values:

$$ 333.99 + 999.8120 - 1980.1026 \approx -646.3006 $$

- Simplify the equation:

$$ -646.3006 = ? \times 2.5 + 5^3 - 23.54^2 $$

- Calculate \(5^3\):

$$ 5^3 = 125 $$

- Calculate \(23.54^2\):

$$ 23.54^2 \approx 554.3716 $$

- Solve for '?':

$$ -646.3006 = ? \times 2.5 + 125 - 554.3716 $$

$$ -646.3006 = ? \times 2.5 - 429.3716 $$

$$ -646.3006 + 429.3716 = ? \times 2.5 $$

$$ -216.9290 \approx ? \times 2.5 $$

$$ ? \approx -86.772 $$

- Round the solution to match options:

$$ ? \approx -87 $$

- No exact match, but closest is Option 5: -78.

So, the correct option is:

Option 5: -78