Question

The variable y is directly proportional tot he variable x. if y=9 when x= 5 what is the value of y when x =20

Answer 1

Explanation:

y is directly proportional to the variable x, so

`y=kx`

Sub in y=9, x=5 to find k:

`9=5k \rightarrow k=(9)/(5)`

So we get:

`y=(9)/(5) x`

Find y when x=20:

`y=(9)/(5) x`

`y=(9)/(5) * 20`

`=36`

SAolution: when x=20, y=36