So the foreign exchange market in Paris is an indirect pricing method!
In the Paris foreign exchange market, you said 30-60 is a premium! Because of the 3-month US dollar forward exchange rate, the difference of the buying exchange rate is smaller than the difference of the selling exchange rate!
In other words, use your light spot +30/60.
Example: spot: USD /ffr6.3240-6.3270.
3-month forward: (6.3240+0.0030)-(6.3270+0.0060)
=6.3270-6.3330