Question

Y is directly proportional to x. If y=15 when x=3,find y when x=30

Pls help​

Answer 1

150

Explanation:

When y is directly proportional to x, y=kx and k=
`(y)/(x)`.

With the corresponding values we already know (3, 15), we can work out k.

k=
`(y)/(x)`, which is k=
`(15)/(3)` or k=5 when using those values.

Now that we know k, we can use it in the equation y=kx to get y.

We can substitute x for 30, as that's what we are working out, and k for 5 (as worked out above) to get y=30×5, which can be solved to y=150.

**This content involves rates of change/direct and inverse proportions, which you may wish to revise. I'm always happy to help!