Let $\sum_1, \sum_2$ be transverse hyperframes to a field $X: U \subset R^n \rightarrow R^n$ of class $C^k$; $k \geq 1$. If $p_i = \psi(t_i) \in \sum_i (i=1,2)$, with $t_1 <t_2$, show that there is a neighborhood $V_i$ of $P_i$ and a function: $\tau : V_1 \cap \sum_1 \rightarrow \mathbb{R}$ such that the application $h : V_1 \cap \sum_1 \rightarrow V_2 \cap \sum_2$ given by $h (q) = \psi (\tau (q), q)$ is one diffeomorphism of $V_1 \cap \sum_1$ in $V_2 \cap \sum_2$.
I know that by the statement itself this question is about applying the tubular flow theorem somehow, but I can not, someone can give a tip