The following system models the winning times, $y,$ in seconds, in the Olympic 500 -meter speed skating event
$x$ years after 1970 :
\left\{\begin{array}{l}
y=-0.19 x+43.7 \\
y=-0.16 x+39.9
\end{array}\right.
Use the slope of each model to explain why the system has a solution. What does this solution represent?