Question

find the value of k if the points (4,2),(7,k),(3,8) are collinear​

Answer 1

answer will be 4 after cross multiplication

Answer 2

$\frac{7 - 4}{k - 7} = \frac{3 - 7}{8 - k} \\ \frac{3}{k - 7} = \frac{ 4}{k - 8} \\ 3k - 24 = 4k - 28 \\ k = 4$

I hope it will be answer of your question