If you mean: 9f+10f-12f then it is 7f simplified
f-18=48-10f 11f-18=48 11f=66 f=6
If: df+10f = 3 Then: f(d+10) = 3 And: d = 3/f -10
0
Suppose f = 2.811... then 10f = 28.111... so that 9f = 25.3 then f = 25.3/9 = 253/90 = 273/90
The value of an 1833 Grootoosten van Belge Grand Orient de Belgique 10f stamp can vary significantly based on its condition, rarity, and demand among collectors. Generally, such historical stamps might be valued anywhere from a few hundred to several thousand dollars. To determine an accurate worth, it's advisable to consult a stamp expert or appraiser and refer to recent auction results or stamp catalog prices.
Apx. $1.50 (USD).
"Belgique" is the French form of "Belgium", but a denomination is needed. Please post a new, separate question with that information.
0-1000 usd
150$
10F 1991
La belgique is Belgium.
If you mean: 5f+10 = 10f then the value of f works out as 2
95209
10f+deepestpart 10f+underground lake
If you mean: 9f+10f-12f then it is 7f simplified
50-500 usd