H(x) equals what? I think you've missed that detail. :)
Make a circle and then another circle. There should be a oval in the middle.
Like this:
https://docs.google.com/drawings/d/10jIdkQW5rnxfDS9T2WeqkwRTvl92oJsYkXVLj8Zn6hU/edit
If you mean unit rate you find it by dividing the top number by the bottom number to fin the singular number or unit rate.
Answer:
A linear equation has the greatest x power at 1.
If you see an equation with only x (no x^2 or x^3 or stuff like that), you will know that it is linear.