Answer
\[\frac{y-b}{x}\].
Work Step by Step
Consider the formula:
\[y=mx+b\].
It is straight line formula for variable m.
Now subtract both side by b.
\[\begin{align}
& y-b=mx+b-b \\
& y-b=mx \\
& \frac{y-b}{x}=m \\
& m=\frac{y-b}{x}
\end{align}\]
Thus, the variable m is\[\frac{y-b}{x}\].
