Question 896183
{{{h(x)=-3x+6}}} is a linear function,
so its graph is a straight line.
The inverse of a function, if it exists,
is another function whose graph is a "mirror" image of the original function.
Linear functions that are not constant have inverses, and the inverses are also linear functions.
{{{graph(300,300,-2,8,-2,8,-3x+6,(6-x)/3,x)}}}  shows the graph of the original function in red, and the graph of the inverse in green.
Each graph is the other one reflected over the blue diagonal line {{{y=x}}} .
That blue line is always the mirror between any function and its inverse