reserve w, w1, w2 for Element of ExtREAL;
reserve c, c1, c2 for Complex;
reserve A, B, C, D for complex-membered set;
reserve F, G, H, I for ext-real-membered set;
reserve a, b, s, t, z for Complex;
reserve f, g, h, i, j for ExtReal;
reserve r for Real;
reserve e for set;

theorem Th100:
  {a,b}**{s,t} = {a*s,a*t,b*s,b*t}
proof
  thus {a,b}**{s,t} = ({a}\/{b})**{s,t} by ENUMSET1:1
    .= ({a}**{s,t}) \/ ({b}**{s,t}) by Th92
    .= {a*s,a*t} \/ ({b}**{s,t}) by Th99
    .= {a*s,a*t} \/ {b*s,b*t} by Th99
    .= {a*s,a*t,b*s,b*t} by ENUMSET1:5;
end;
