TeX source:

\begin{gathered} \text { slope }=\frac{\Delta v}{\Delta t}=\frac{(260 \mathrm{~m} / \mathrm{s}-210 \mathrm{~m} / \mathrm{s})}{(51 \mathrm{~s}-1.0 \mathrm{~s})} \\ a=\frac{50 \mathrm{~m} / \mathrm{s}}{50 \mathrm{~s}}=1.0 \mathrm{~m} / \mathrm{s}^{2} \end{gathered}