Answer:
[tex]\boxed{a = 3}[/tex]
Step-by-step explanation:
[tex] (using \: the \: points : (2, \: 7) = ( x_{1}, \: y_{1}\: \: ) \\ hence : (a, \: 2) = ( x_{2}, \: y_{2}\: \: ) \\ but \: m = \frac{ y_{2} -y_{1} }{x_{2} - x_{1}} = \frac{2 - 7}{a - 2} \\ - 5 = \frac{2 - 7}{a - 2} \\ - 5(a - 2) = 2 - 7 \\ - 5a + 10 = 2 - 7 \\ - 5a = - 5 - 10 \\ - 5a = - 15 \\ a = \frac{ - 15}{ - 5} \\ \boxed{a = 3}[/tex]
