Question

Y varies directly as xy equals 5 when X is 8 how do you find y when X is 9

Answer 1

Given, y varies directly as x

So,

`y=c\cdot x`

Where c is a constant

When y equals 5 when x is 8

So,

`\begin{gathered} 5=c\cdot8 \\ c=(5)/(8) \\ \end{gathered}`

So, the relation between y and x

`y=(5)/(8)x`

now , when x = 9

Substitute with x to find y

`y=(5)/(8)\cdot9=(45)/(8)`

So, the answer is option 2. y = 45/8