|For the graph of $f$ and $g$: Find the point at the intersection of the graphs of $f$ and $g$, $(x_*,y_*)$, determine it's first coordinate, $x_*$, and that is the desired value for $x$, and its second coordinate, $y_*$, is the desired value for $y$.||For the mapping diagram of $f$ and $g$: Find the focus points of $f$, $F= [m_f, b_f]$, and $g$, $G=[m_gb_g]$, on the
mapping diagram. Draw the line through $F$ and $G$, to
find the point of intersection of this line with the X axis, $x=x_*$,
which is the desired
value for $x$ and the Y axis, $y=y_*$ for the desired value of $y$. Notice how the point on the graph is paired with the points and arrow on the mapping diagram.
Martin Flashman, Aug. 11, 2018, Created with GeoGebra