Source TeX:

v(t) = \left\{ {\begin{array}{cll} \frac{5}{3} t&\text{si}& 0 \leq t \leq 10 \\[0.8em] \frac{50}{3}&\text{si}&10 < t < 25 \\[0.8em] \frac{50}{3} -\frac{25}{6}\left({ t-25}\right)&\text{si}&25 \leq t \leq 29 \end{array}}\right.