What is the sum of the polynomials?

1. Remove Parentheses: Since we are adding the polynomials, we can remove the parentheses without changing the signs of the terms.
$$(1.3t^3 + 0.4t^2 - 24t) + (8 - 18t + 0.6t^2)$$ becomes $$1.3t^3 + 0.4t^2 - 24t + 8 - 18t + 0.6t^2$$

2. Group Like Terms: Identify terms with the same variable and exponent and group them together.
$$1.3t^3 + (0.4t^2 + 0.6t^2) + (-24t - 18t) + 8$$

3. Combine Like Terms: Add or subtract the coefficients of the like terms.
For the $t^3$ terms: There is only one term, $1.3t^3$.
For the $t^2$ terms: $0.4t^2 + 0.6t^2 = (0.4 + 0.6)t^2 = 1.0t^2 = t^2$.
For the $t$ terms: $-24t - 18t = (-24 - 18)t = -42t$.
For the constant terms: There is only one constant term, $8$.

Combining these results, we get: $$1.3t^3 + t^2 - 42t + 8$$