<image>Temperature is closely related to our lives. Have you ever carefully observed a thermometer? The figure shows a schematic diagram of a thermometer. The scale on the left is Celsius temperature $$(℃)$$, and the scale on the right is Fahrenheit temperature $$(℉)$$. Let Celsius temperature be $$x(℃)$$ and Fahrenheit temperature be $$y(℉)$$. Then $$y$$ is a linear function of $$x$$.
$$(1)$$ Carefully observe the data in the figure and find the functional expression between $$y$$ and $$x$$;
$$(2)$$ When the Celsius temperature is minus $$15℃$$, what is the corresponding Fahrenheit temperature?