15*(30 - j40) ------------- + 30 - j40 15
(15*(30 - j40))/15 + 30 - j40 при j40 = 1/3
(15*(30 - j40))/15 + 30 - j40
(15*(30 - (1/3)))/15 + 30 - (1/3)
(15*(30 - 1/3))/15 + 30 - 1/3
178/3
60 - 2*j40
60.0 - 2.0*j40
2*(30 - j40)
-2*(-30 + j40)