Answer:
I found the equation (through a lot of guessing on d e s m o s .com), but not really sure how to explain how I got the answer, i learned how to do it a couple years ago but now i forgot, sorry about that.
the equation is h(t) = -1/1.5 * (x - 3)^2 + 10
There is a formula for it but I forgot the exact formula of the values, but this is the equation definitely.
I hope this helps some, sorry i couldn't do more!