Question 997632

Points (1,3) (-4,7) and (-29, k) are collinear. Find k. So, I found the slope of the first two points they gave me, I just don't understand what to do with it from there.
<pre>Any 2 points will give you the same slope, since all points are collinear
m, or slope = {{{(3 - 7)/(1 - - 4)}}} --------> {{{- 4/5}}}
Therefore, {{{(k - 7)/(- 29 - - 4) = - 4/5}}} -----> {{{(k - 7)/(- 25) = - 4/5}}}
5(k - 7) = - 4(- 25) -------- Cross-multiplying
5k - 35 = 100
5k = 100 + 35
5k = 135
k = {{{135/5}}}, or {{{highlight_green(k = 27)}}}