Răspuns :
10 × 3 × 9 - 30 : 3 : 10 + 11 = 7f
30 × 9 - 10 : 10 + 11 = 7f
270 - 1 + 11 = 7f
269 + 11 = 7f
280 = 7f
f = 280 : 7
f = 40
30 × 9 - 10 : 10 + 11 = 7f
270 - 1 + 11 = 7f
269 + 11 = 7f
280 = 7f
f = 280 : 7
f = 40