А) 24и(4/5) - [19,5:(7и2/9)] = (124/5) - [(19и5/10):(7и2/9)] = (124/5) - [(195/10)*(9/65)]=(248/10) - (27/10) = (221/10) = 22и(1/10)
б) 2,4 + 5,6*[(13и3/4) - (12и13/14)] = (24/10) + (56/10)*[(55/4) - (181/14)] = (24/10) + (56/10)*[(385/28) - (362/28)] = (24/10) + (56/10)*(23/28) = (24/10) + (46/10) = (70/10) = 7