<<xlr8r.m

model={{(Overscript[A⇄B, ℰ]),a,d,k}};
IC={A-> 1,B-> 0,ℰ-> 1};
parameters={a-> 1, d-> .1, k-> 2}; 
sim=run[model,timeSpan-> 5,initialConditions-> IC, 
rates-> parameters];
runPlot[sim]

runPlot[sim,{A,B},holdLegend-> True,Frame-> True,PlotStyle-> {Brown, Green},BaseStyle-> {FontSize-> 18,FontFamily->"Verdana"}]