Circuit Theory/Thevenin-Norton/code2

numeric::linsolve([
(1-va)/5 - (va-vb)/2 - va/7,
(1-vb)/3 + (va-vb)/2 - vb/10,
current = (1-va)/5 + (1-vb)/3],[va,vb,current])

[va = 0.6583850932, vb = 0.7098491571, current = 0.165039929]

current = 0.165039929;
vs = 1;
Req = vs/current