[overkille]

x=sym('x');
y= 6000*(x/14)^3;
z= 160*(x/14)^3;
s1= 1850;
t1= s1/(24*x);
t2= 2*t1;
t3= t2+1;
m1= 239/t3;
%-------------------------------------------------------------
n1=y*z*10^-6/24;
n2=n1*t1;
n3=m1*n1*t2;
f1=30000-n2;
f2=m1*f1;
%---------------------------------------------------------------
p1=625;
k1=p1*n3;
c1=6000;
k2=c1*240;
b1=5342;
k3=b1*240;
g=0;
%------------------------------------------------------------------
r=10;
%r=(k1+k2+k3+g)/f2; % RFR
f=(k1+k2+k3+g)-f2*r;
%------------------------------------------------------------------
solve(f);


还有就是，如果想画出r和x的曲线图，如何写函数？
非常感谢。