$$\left. \begin{array} { l } { U = \{ x : x N , x \leq 10 \} } \\ { B = \{ t h e n , } } \end{array} \right.$$
$x\in (-\infty,0)\cup (0,10]\text{, }U=N\text{ and }B=ehnt$
$\left\{\begin{matrix}t\in \mathrm{R}\text{, }&\left(n=0\text{ or }h=0\right)\text{ and }U=N\text{ and }x\leq 10\text{ and }B=0\text{ and }x\neq 0\\t=\frac{B}{ehn}\text{, }&U=N\text{ and }x\leq 10\text{ and }n\neq 0\text{ and }h\neq 0\text{ and }x\neq 0\end{matrix}\right.$
