Manipulate[data={{0.006,0.007},{0.006,0.008},{0.012,0.009},{0.027,0.020},{0.056,0.026},{0.111,0.030},{0.280,0.033}};Plot[((a x)/(b+x)),{x,0,.28},PlotRange->{-.002,0.045},PlotStyle->Black,AxesLabel->{N,R},Epilog->{{Arrow[{{.01,((3 a)/4)},{.01,(a/2)}}],Arrow[{{.01,((3 a)/4)},{.01,a}}]},Text[Style["50%",Black],{0.02,.75 a}],Text[Style["S",Blue,Medium],{-0.004,a}],Text[Style["c",Green,Medium],{b+.001,-.0015}],{Red,PointSize[Large],Point[data]},{Blue,Dashed,Line[{{0,a},{.3,a}}]},{Green,Dashed,Line[{{0,(a/2)},{b,(a/2)}}],Line[{{b,(a/2)},{b,0}}]}}],{{a,0.0358, "Maximum, S"},0.015,0.045, Appearance-> "Labeled"},{{b,0.021, "Half-saturation value, c"},0.01,0.2, Appearance-> "Labeled"}]