16. (5 points) A fraction, if the denominator is reduced by 1, simplifies to $\frac{1}{3}$; if the numerator is increased by 4, it simplifies to $\frac{1}{2}$. What is this fraction?
【Solution】Solution: Let the original fraction be $\frac{\mathrm{y}}{\mathrm{x}}$, then:
$$
\frac{y}{x-1}=\frac{1}{3}
$$

So, $3 y=x-1$
$$
x=3 y+1 \text {; }
$$
$$
\begin{array}{l}
\frac{y+4}{x}=\frac{1}{2} \\
x=2 y+8,
\end{array}
$$

Then:
$$
\begin{array}{c}
3 y+1=2 y+8 \\
3 y-2 y=8-1 \\
y=7 \\
x=2 \times 7+8=22
\end{array}
$$