Manipulate[ F[Ct, Mt]:= (Tf(MpCp+MtCt)-MtCtTi)/(MpCp); y = (Tf(MpCp+MC)-MCTi)/(MpCp); (redefined Ti equation)

Plot[{Callout[{F[Ct, Mt]}, "Cobalt Chrome",0.39],
Callout[{F[Ct, Mt]}, "Stainless Steel",0.468],
Callout[{F[Ct, Mt]}, "Titanium",0.523]},
{Ct, 0.3, 0.6},
PlotLabel-> Style["Mass of Surgical Tool v. Temperature Required for Steralization", Fontsize->18],
AxesLabel-> {
    Style["Heat Capacity (J/g\[Degree]C)", Orange],
    Style["Temperature to Steralize Surgical Tool (\[Degree]C)", Red]
    }
    ,  
PlotRange->{{0.3, 0.6}, {Tmin, Tmax}},
ImageSize->500
],
    Text[Style[Grid[{
{"\[Degree]C to Steralize Cobalt Chrome Surgical Tool", (Tf*(Mp*Cp+M*0.39)-M*0.39*Ti)/(Mp*Cp)     },
{"\[Degree]C to Steralize Stainless Steel Surgical Tool",  (Tf*(Mp*Cp+M*0.468)-M*0.468*Ti)/(Mp*Cp)},
{"\[Degree]C to Steralize Titanium Surgical Tool", (Tf*(Mp*Cp+M*0.523)-M*0.523*Ti)/(Mp*Cp)}
}, Alignment->Left, Frame->All],  FontSize->12]],
Control[{{M, 5, "Mass of Surgical Tool (g)"}, 5, 2500, Appearance-> "Labeled"}],
ContentSize->{600, 300}
]

I am having trouble with successfully displaying the function output of F[Ct, Mt] in my text style grid. I have tried to redefine the function differently but the same problem still persists where the text style grid does not recognize the variable M. I have attached the constants and working text style grid below. Any help would be greatly appreciated.

(*Physical Constants*)
Mp=800; (*g for the mass of hotplate*)
Cp=0.89; (*J/gc heat capacity for hotplate*)
Tf=160; (*c desired final temp*)
Ti=25; (*c initial temp for surgical tool*)

 (*Ranges*)
 Tmin=100; (*minimal temperature of hotplate*)
 Tmax=450; (*maxmial temperature of hotplate*)
 Mmin=5; (*g minimal surgical tool weight*)
 Mmax=2500; (*g maxmimum surgical tool weight*)


(*Initial hotplate Temperature Equation*)
F[Ct_, Mt_]:= (Tf*(Mp*Cp+Mt*Ct)-Mt*Ct*Ti)/(Mp*Cp);

(*Manipulate-Friendly Equation*)
Ct=c; (*redefined Ct as c*)
Mt=M; (*redefined Mt as M*)
y = (Tf*(Mp*Cp+M*C)-M*C*Ti)/(Mp*Cp); (*redefined Ti equation*)


Manipulate[
y = (Tf*(Mp*Cp+M*C)-M*C*Ti)/(Mp*Cp); (*redefined Ti equation*)
Text[Style[Grid[{
{"\[Degree]C to Steralize Cobalt Chrome Surgical Tool", (Tf*(Mp*Cp+M*0.39)-M*0.39*Ti)/(Mp*Cp)},
{"\[Degree]C to Steralize Stainless Steel Surgical Tool",  (Tf*(Mp*Cp+M*0.468)-            M*0.468*Ti)/(Mp*Cp)},
{"\[Degree]C to Steralize Titanium Surgical Tool", (Tf*(Mp*Cp+M*0.523)-M*0.523*Ti)/(Mp*Cp)}
}, Alignment->Left, Frame->All],  FontSize->12]],
Control[{{M, 5, "Mass of Surgical Tool (g)"}, 5, 2500, Appearance-> "Labeled"}],
ContentSize->{600, 300}
]

Attachments:

Mathematica Demo...nb