If line thru (a,1), (6,5) parallel to line thru (9,6), (a+7,

[derek916]

If the line passing through the points (a, 1) and (6, 5) is parallel to the line passing through the points (9, 6) and (a + 7, 1), what is the value of a?

I know that they need to have either the same slope, but I have no idea how to do this problem

My work
5-1/6-a = 4/6-a
1-6/a+7-9 = -5/a-2

After that...I'm lost

[stapel_eliz]

I know that they need to have...the same slope....
My work
5-1/6-a = 4/6-a
1-6/a+7-9 = -5/a-2

After that...I'm lost

Now use the fact that the slopes (and thus the slope expressions you have derived) are the same (that is, equal). Solve the resulting equation for the value of "a".