f-354=1221
the answer would be
f = 1,575. this is because you would add 354 to 1221 and the answer to that, and the answer, in general, is 1575. Also, 1575 - 354 = 1221.
So, in conclusion, f = 1575 because f - 345 + 354 = 1221 + 354.
your turn
Bosnian has done several of these for you by now.