A]
[808-a]×2=418
808-a=418÷2
808-a=209
a=808-209
a=599
VERIFICARE
[808-a]×2=418
b]
[777-a]-258=220
777-a=220+258
777-a=478
a=777-478
a=299
VERIFICARE
[777-299]-258=220
c]
[9191-a]+687=2000
9191-a=2000-687
9191-a=1313
a=9191-1313
a=7878
VERIFICARE
[9191-7878]+687=2000
SUCCES