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if RadioButton1.Checked = true then 
begin
  // von Euro nach Dollar...
  Edit1.Text := IntToStr(StrToInt(Edit1.Text)*Wechselkurs);
end else
begin
  // von Dollar nach Euro...
  Edit1.Text := IntToStr(StrToInt(Edit1.Text)*Wechselkurs2);
end;                    

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if (RadioGroup1.ItemIndex = 1) and (RadioGroup2.ItemIndex = 2) then
begin
  // Euro-Dollar
  // ...
end else
if (RadioGroup1.ItemIndex = 1) and (RadioGroup2.ItemIndex = 3) then 
begin
  // Euro-Pfund
  // ...
end else
if (RadioGroup1.ItemIndex = 1) and (RadioGroup2.ItemIndex = 4) then 
begin
  // Euro-Yen
  // ...
end else
if (RadioGroup1.ItemIndex = 2) and (RadioGroup2.ItemIndex = 1) then 
begin
  // Dollar-Euro
  // ...
end else
...                    

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const
ed:1.30350;
eb:0.69085;
esf:1.54790;
de:0.76728;
db:0.52991;
dsf:1.18770;
be:1.44865;
bd:1.88710;
bsf:2.24150;
sfe:0.64629;
sfd:0.84196;
sfb:0.44613;                    

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const
ed=1.30350;
eb=0.69085;
esf=1.54790;
de=0.76728;
db=0.52991;
dsf=1.18770;
be=1.44865;
bd=1.88710;
bsf=2.24150;
sfe=0.64629;
sfd=0.84196;
sfb=0.44613;