If y varies directly with x, and If y = -18 when x = 6, how do you find x when y = 6?

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Answer 1 · 2015-12-11T14:06:00

Another way of looking at this problem type

$x = - 2$ $x=-2$

Firstly, the solution provided already is correct in its approach and it has many applications.

Let us consider the use of the constant conversion factor of k

This is where the use of k comes from
Suppose we had for example $2/3-> k ~~ 0.666....$

Now compare that concept to:

$x/y=6/(-18)$ if you divide this out you end up with k

What if we wrote it as:

$x/y=6/(-18) =x/6$

Then the solution is presented in the familiar form of ratio

Multiply both sides by 6 and you end up with:

$6xx6/(-18)=6xx x/6$

$(6xx6)/(-18)=6/6 x$

$x=-36/18 = -2$

Either of the approaches will work