2. (5 points) Given $a=0.5, b=\frac{1}{3}$, then $a-b$ is $\frac{1}{78}$ of $\qquad$ times

保留源文本的换行和格式，翻译结果如下：

2. (5 points) Given $a=0.5, b=\frac{1}{3}$, then $a-b$ is $\frac{1}{78}$ of $\qquad$ times
【Solution】Solve: $(a-b) \div \frac{1}{78}$
$$
\begin{array}{l}
=\left(0.5-\frac{1}{3}\right) \div \frac{1}{78} \\
=\left(\frac{1}{2}-\frac{1}{3}\right) \div \frac{1}{78} \\
=\frac{1}{6} \div \frac{1}{78} \\
=13
\end{array}
$$

Therefore, the answer is: 13.