Question

If y varies directly as x, and y = 14 as x = 7, find y for the x-value of 10.

Answer 1

While I can't be 100% sure, I believe that this is how you would solve this problem:
x=7, and y=14. As y varies directly as x, y=2(x), seen through 2(7)=14.
Therefore, when x=10, y=2(10)=20
And so, y= 20.

Answer 2

Just for terminology:
y varies directly with x...
`y = kx`
y varies directly with x²...
`y = kx²`
y varies indirectly with x...
`y = k/x`

We need to find the constant
`k` in the equation
`y=kx`.

Plug in the known values.
`14=k\dot7`...
`k=2`.

Now, you have your equation.
`y=2x`.

Plug in 10 for
`x`.


`y=2\dot10=\box{20}`