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,

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

Now,

Find x when y is 9

So,

$\begin{gathered} y=kx \\ 9=\frac{1}{5}x \\ 45=x \end{gathered}$

Hence, the value of x is 45.