Math

Question

If the line passing through the points (1,a) and (4,-2)is parallel to the line passing through the points (2,8) and (-7,a + 4), What is the value of a ? Please help, I don't understand how to set this one up.

Answer 1

If they are parallel, they have the same slope.

line slope=(a+2)/(-3)
second line slope=(-a+4)/(9)
set them equal and solve for a.