\(\bf \begin{array}{lllll}
1.3t^3&+0.4t^2&-24t\\\\
0t^3&-0.6t^2&+18t&-8\\\\
--&--&--&--\\
1.3t^3&-0.2t^2&-6t&-8\\
A&B&C&D
\end{array}\)
if you were to align those two polynomials vertically, you'd align the like-terms, below each other like so, if that helps
