[tex]\begin{gathered} P=86.94\text{ kgm/s} \\ v=2.3\text{ m/s} \\ m=? \\ P=mv \\ Solving\text{ m} \\ m=\frac{P}{v} \\ m\frac{86.94\text{ kgm/s}}{2.3\text{ m/s}} \\ m=37.8\text{ kg} \\ Thr\text{ mass of the child and skateboard is 37.8kg } \end{gathered}[/tex]
