[tex]\bf \begin{array}{lllll}
&x_1&y_1&x_2&y_2\\
% (a,b)
&({{ 50}}\quad ,&{{ 14.01}})\quad
% (c,d)
&({{ 79}}\quad ,&{{ 17.78}})
\end{array}
\\\quad \\\\
% slope = m
slope = {{ m}}= \cfrac{rise}{run} \implies
\cfrac{{{ y_2}}-{{ y_1}}}{{{ x_2}}-{{ x_1}}}
\\ \quad \\\\
% point-slope intercept
y-{{ y_1}}={{ m}}(x-{{ x_1}})\qquad \textit{plug in the values and solve for "y"}\\
\qquad \uparrow\\
\textit{point-slope form}[/tex]
find the slope, or "rate of change", then plug those values in the
point-slope form and solve for "y", to get the equation of that line,
how much is it for 73 minutes? well, make x = 73, and to get "y" :)
