Răspuns :
2 + b x 9 - 25 = 40
2 + b x9 = 40 + 25
2 + b x 9 = 65
b x 9 = 65 - 2
b x9 = 63
b = 63 : 9
b = 7
2 + b x9 = 40 + 25
2 + b x 9 = 65
b x 9 = 65 - 2
b x9 = 63
b = 63 : 9
b = 7