ans =

The real values of Rn, Rp and Rx should be 2e6,1.5e5 and 700k.

Those are inconsistent with the equations.

Rn = 2e6;

Rp = 1.5e5;

Rx = 700e3;

syms V1 V2 Vp Vn Vxp Vxn Vpx Vnx

Ison=((Vp/((Rp*68220)/(Rp+68220)))-(Vxp/((Rx*68220)/(Rx+68220))));

equ1=Vp==(V1+V2)-Ison*Rn;

Isop=((Vn/((Rn*68220)/(Rn+68220)))-(Vxn/((Rx*68220)/(Rx+68220))));

equ2=Vn==(V1+V2)-Isop*Rp;

Isox=((Vnx/((Rn*68220)/(Rn+68220)))-(Vpx/((Rp*68220)/(Rp+68220))));

equ3= Vpx==V1+Rx*Isox;

eqns = [equ1; equ2; equ3]

sol = subs(eqns, {V1,V2,Vp,Vn,Vxp,Vxn,Vpx,Vnx}, {270,270,144.56868,147.38892,125.43132,122.61108,268.58987,271.41013})

vpa(lhs(sol) - rhs(sol))

%above should be quite close to zero if the equations are consistent.