Cartesian Equation question

Can someone help me with this question? I'm not sure whether there are other steps i need to take or not

Find the values of the parameters and the other co-ordinates of the given points on this curve:
x=at^2 and y=2at where x=9a/4

Ive already rearranged the second equation and made it equal to x, and then subbed it into the first equation to get 4ax=y^2
I then rearranged the 3rd equation to get 4x/9=a and subbed it into 4ax=y^2 which gave me 16x^2=9y^2

Do i need to draw any graphs? is that even right?also unfortunately i can't take any pictures of my working out as my phone is broken

You're making this too complicated

If x = at^2 and x = 9a/4, what value(s) can the parameter t take? And then what are the corresponding value(s) of y?