How do I write part of a equation which is predefined in a variable?

syms t;

vg= int( f*sin(o*t)/m);

xg= int(vg);

Is storing the integrated form of my equation in symbolic form in 'xg'.

Now I want to use the equation stored in 'xg' in another equation, say-

eqn1= -1/(Mw*Phi)*(Md*g-Psi*Md/Mw*tan(theta)*(x(1)-xg)+Ks*(y_bar+(x(1)-x(3))*tan(theta)))-Psi/Mw*(x(1)-xg);

Further this eqn1 is solved using ode45().

How do I write this 'eqn1' ??

I am getting following error.

Undefined function 'int' for input arguments of type
'double'.

Error in eqns_v3a (line 34)
vg= int(ag);   % Ground Velocity

Error in odearguments (line 87)
f0 = feval(ode,t0,y0,args{:});   % ODE15I sets
args{1} to yp0.

Error in ode45 (line 115)
    odearguments(FcnHandlesUsed, solver_name, ode,
    tspan, y0, options, varargin);

Error in Wedge_damper_v5 (line 28)
        [t,x] = ode45(@eqns_v3a,t,x0);  % Left Face