Question

If x varies directly as y, and x = 30 when y = 6, find x when y = 9.

Answer 1

As given by the question

There are given that the x varies directly as y.

That means,

As y increases, x will increase and y decreases, x will decrease.

Now,

From the formula:

`y=kx`

Then,

Fromthe given question,

x is 30 when y is 6

So,

`\begin{gathered} y=kx \\ 6=k(30) \\ k=(6)/(30) \\ k=(1)/(5) \end{gathered}`

Now,

Find x when y is 9

So,

`\begin{gathered} y=kx \\ 9=(1)/(5)x \\ 45=x \end{gathered}`

Hence, the value of x is 45.