The equation of the line passing through point $ \left(721,~182\right) $, and point $ \left(\dfrac{ 3473 }{ 5 },~\dfrac{ 838 }{ 5 }\right) $ is:
$$ y = \frac{ 6 }{ 11 } x - \frac{ 2324 }{ 11 } $$To find equation of the line passing through points $ A(x_A,y_A) $ and $ B(x_B,y_B) $, we use formula:
$$ y - y_A~=~\frac{y_B - y_A}{x_B - x_A}(x-x_A) $$In this example we have:
$$ \begin{aligned} & \left(721,~182\right) \implies x_A = 721 ~~\text{and}~~ y_A = 182 \\[1 em] & \left(\dfrac{ 3473 }{ 5 },~\dfrac{ 838 }{ 5 }\right) \implies x_B = \frac{ 3473 }{ 5 } ~~\text{and}~~ y_B = \frac{ 838 }{ 5 } \end{aligned} $$After substituting into the formula, we obtain:
$$ \begin{aligned} y - y_A~&=~\frac{y_B - y_A}{x_B - x_A}(x - x_A) \\[1 em] y - 182~&=~\frac{ \frac{ 838 }{ 5 } - 182 }{ \frac{ 3473 }{ 5 } - 721 } \left( x - 721 \right) \\[1 em]y - 182 ~&=~ \frac{ 6 }{ 11 } \left( x - 721 \right) \\[1 em]y - 182 ~&=~ \frac{ 6 }{ 11 }x-\frac{ 4326 }{ 11 } \\[1 em]y ~&=~ \frac{ 6 }{ 11 }x-\frac{ 2324 }{ 11 } \end{aligned} $$