Solve system of equations

I have a system of seven equations. The equations are dependent on a variable called "Ptot". There are four constants across the equations.

I am trying to solve the seven equations to get th value of Ptot. I tried the following code but I am getting a message "Empty sym: 0-by-1".

Could you please help me?

Best Regards,

Dipen

syms Ptot P1 P2 P_vert P_horiz V H 

a=deg2rad(-37.9);       %(deg)+ve for upslope and -ve for downslope angle of shear plane
t1=deg2rad(37.9);       %(deg) angle of P1 with Horizontal
t2=deg2rad(23);         %(deg) angle of P2 with horizontal
Wc=0.74;                %(kN) Weight of concrete 

eqn1=P1==0.55*Ptot;
eqn2=P2==0.45*Ptot;
eqn3=P_vert==P1*sin(t1)+P2*sin(t2);   
eqn4=P_horiz==P1*cos(t1)+P2*cos(t2);
eqn5=V==Wc+P_vert; 
eqn6=H==P_horiz;    
eqn7=H*cos(a)-V*sin(a)==40;

eqns=[eqn7 eqn6 eqn5 eqn4 eqn3 eqn2 eqn1];

P=solve(eqns,Ptot)

Answer 1

[Walter Roberson]

You are asking to solve all of the equations in terms of one variable. Instead just

sol=solve(eqns) ;
P=sol.Ptot