I am trying to learn using Maple 18 (Mac).
I have defined a function with a list of X and Y values.

> 
> f := x->LinReg(X, Y, x)
> 
> 
> 

Now I would like to output the unknown "x" value that correlates with a known "y" value (e.g. 30).
According to the instruction manual, that I have, the way to do it is using this command:

![Output x command](https://i.stack.imgur.com/ddHqZ.png)

I just can't figure out how to type "solve" with an arrow under it.

Any help would be appreciated.

EDITED:
Screenshot of the commandwindow
![Screenshot of the commandwindow](https://i.stack.imgur.com/XWweL.png)