Question

If the line passing through the points (a, 1) and (−2, 6) is parallel to the line passing through the points (−12, 9) and (a + 2, 1), what is the value of a?

Answer 1

$\frac{6 - 1}{ - 2 - a} = \frac{9 - 1}{ - 12 - a - 2} \\ \frac{5}{ - 2 - a} = \frac{8}{ - 14 - a} \\ 16 + 8a = 70 + 5a \\ 3a = 54 > > a = 18$