[ f(x) = \begin{cases} 0.793x & \text{si } 0 \leq x \leq 75 \ 0.793 \cdot 75 + 0.956(x - 75) & \text{si } 75 < x \leq 140 \ 0.793 \cdot 75 + 0.956 \cdot 65 + 2.802(x - 140) & \text{si } x > 140 \end{cases} ]