How do I use the ShowLegends function to produce a legend for my framed graphic?

Question

I'm new to this site and new to Mathematica as you can see from my question. I'm also new to programming, btw.

I'm trying to produce a legend for my plot which I've coded as follows:

Needs["PlotLegends`"]
ds1 = {{0, 0.53}, {10, 1.00}, {20, 2.19}, {35, 3.61}};
ds2 = {{0, 0.52}, {10, 0.91}, {20, 1.97}, {35, 3.09}};
ds3 = {{0, ds1[[1, 2]] - ds2[[1, 2]]}, 
       {10, ds1[[2, 2]] - ds2[[2, 2]]}, 
       {20, ds1[[3, 2]] - ds2[[3, 2]]}, 
       {35, ds1[[4, 2]] - ds2[[4, 2]]}
      };
mf1 = LinearModelFit[ds1, x, x];
mf2 = LinearModelFit[ds2, x, x];
mf3 = LinearModelFit[ds3, x, x];
m1 = mf1["BestFit"]; m2 = mf2["BestFit"]; m3 = mf3["BestFit"];

Show[
  {
    ListPlot[{ds1, ds2, ds3}, 
       PlotMarkers -> Automatic, PlotStyle -> {Blue, Red, Orange}
    ], 
    Plot[{m1, m2, m3}, {x, 0, 35}, PlotStyle -> {Blue, Red, Orange}]
  }, 
  Frame -> True, 
  FrameLabel -> {"Time (min)","Inorganic Phosphate Concentration (mM)"},
  ImageSize -> {400, 300}
]

So, I'd like to use the ShowLegend function to have the legend displayed outside of the frame. I know that I can use the LegendPosition function to do this.

My problem, however, is the tags. How do I get the legend to show the names of the plots (ds1, ds2, ds3, m1, m2, and m3)?

Answer 1

Something like this?

ShowLegend[
 Show[{ListPlot[{ds1, ds2, ds3}, PlotMarkers -> Automatic, 
    PlotStyle -> {Blue, Red, Orange}], 
   Plot[{m1, m2, m3}, {x, 0, 35}, PlotStyle -> {Blue, Red, Orange}]}, 
  Frame -> True, 
  FrameLabel -> {"Time (min)", 
    "Inorganic Phosphate Concentration (mM)"}, ImageSize -> {500}],
 {{
   {Style["\[FilledCircle]", 12, Blue], "ds1"},
   {Style["\[FilledSquare]", 12, Red], "ds2"},
   {Style["\[FilledDiamond]", 12, Orange], "ds3"},
   {Graphics@{Blue, Line[{{0, 0}, {1, 0}}]}, "m1"},
   {Graphics@{Red, Line[{{0, 0}, {1, 0}}]}, "m2"},
   {Graphics@{Orange, Line[{{0, 0}, {1, 0}}]}, "m3"}
   }, LegendPosition -> {1, -0.4}}
 ]