[tex] 8t^{2} [/tex] isn't like any of the other terms because it is being raised to the second power, so you can leave it alone.
-2t + 5t are like terms because they are both coefficients with the variable t. You can combine these to get 3t.
The only term left is -4, so that will remain the same.
Now, you can combine all of these terms to get [tex] 8t^{2} [/tex] + 3t - 4.
