First of all, I am new ,so hello.
now to the topic:
is the formula for direct variation y=kx
and could you please post examples?
Let r be the constant of variation.
The distance (d) varies directly as time (t) if r remains constant. In other words, when t increases, d increases. When t decreases, d decreases.
Follow some of the links I gave you and you'll see other examples.
Also, investigate inverse and joint variation as well.