Too many symbolic variables using fplot

My code won't plot a graph I think because it says I have too many symbolic variables but I only have t as a symbolic varable. I don't know how to fix this error message, please help!

This is my code:

syms t w_1 w_2 'real'
%creates the symbolic and real variables t w_1 and w_2 in matlab and stores them 
x_t = 1.2*cos(w_1*t - 0.85) + 0.35*cos(w_2*t + 0.75)
%creates function pof oscillation

%%part b
w_1 = 0.85
w_2 = 0.20
subs(x_t,{w_1,w_2},{double(0.85),double(0.20)})
%subsitutes the values of w_1 and w_2 with the values I give it 
%the double function changes the symbolic varable type to a double variable
%type
fplot(x_t,[0, 130])

This is my error message
Error using fplot>singleFplot (line 229)
Input must be a function or functions of a single
variable.
Error in
fplot>@(f)singleFplot(cax,{f},limits,extraOpts,args)
(line 193)
        hObj = cellfun(@(f)
        singleFplot(cax,{f},limits,extraOpts,args),fn{1},'UniformOutput',false);
        Error in fplot>vectorizeFplot (line 193)
        hObj = cellfun(@(f)
        singleFplot(cax,{f},limits,extraOpts,args),fn{1},'UniformOutput',false);
        Error in fplot (line 163)
    hObj =
    vectorizeFplot(cax,fn,limits,extraOpts,args);
Error in gerberdolan_jessica_hw10 (line 51)
fplot(x_t,[0, 130]) 

this is what my whos looks like

  t         1x1                 8  sym                 
  w_1       1x1                 8  double              
  w_2       1x1                 8  double                            
  x_t       1x1                 8  sym  

Answer 1

[madhan ravi]

syms t w_1 w_2 real
x_t = 1.2*cos(w_1*t - 0.85) + 0.35*cos(w_2*t + 0.75)
w_1 = 0.85
w_2 = 0.20
x_t=subs(x_t)
fplot(x_t,[0, 130])

[Jessica Gerberdolan]

It worked! thank you!!!

[madhan ravi]

Anytime :)