Estimating an X Value with a Known Y Value in Excel

[2slowtogofast]

I have a graph in excel and i need to estimate an x value with a known y value. Pretty much i need to draw a horizontal line at y= given value over to my data line. Then a vertical line down to find the x value. How can i do this?

 

[danago]

Im not sure what version of excel you are using, but you could go "Insert >> Shapes" and then select the line and manually draw the lines and adjust as necessary. I am not sure if there is a better way.