1. **State the problem:** Simplify the expression $$6t^2 + (-10t^2) + (-4t^2) + (-10t^2) + 8t^2 + (-8t^2)$$. 2. **Combine like terms:** Since all terms are multiples of $t^2$, we can add their coefficients. 3. Write the sum of coefficients: $$6 + (-10) + (-4) + (-10) + 8 + (-8)$$ 4. Simplify step-by-step: $$6 - 10 = -4$$ $$-4 - 4 = -8$$ $$-8 - 10 = -18$$ $$-18 + 8 = -10$$ $$-10 - 8 = -18$$ 5. So the sum of coefficients is $$-18$$. 6. Therefore, the simplified expression is: $$-18t^2$$. **Final answer:** $$-18t^2$$.