Question on: JSS3 Mathematics - Variations

Given 𝑦=𝑘𝑥, substituting the given values:

9=𝑘⋅6

Solving for 𝑘:

𝑘=9/6=1.5

Now, find 𝑦 when 

x=12:

𝑦=1.5⋅12=18