# How to add labels to a graph [duplicate]

This should be an easy question but since few examples are given for ShowLegend and I am a new user, I got stuck after many attempts.

I plot three graphs which are seperately defined as t1, t2, t3. In each graphs there are one or two curves (Original codes to yield the graphs are complicated and not important). Then I present them in one graph, coding

graph1 = Show[t1, t2, t3, PlotRange->All]


Now I would like to add texts for identification for each curve in the graph1, in a form like

  --- x=2
___ x=3
''' x=4


Since the graph1 has already been plotted, PlotLegend may not work. I used ShowLegend but don't know how to establish the codes. Many thanks in advance.

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