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 $x$.

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