12a-3b и 3b-12a при а=-3/4 b=5/6

12a-3b a=3/4 b= 5/612*3/4-3*5/6=36/48-15/18=2/48-15/1=1/24-15/1=1/24-360/24= -359/24360/24-1/24= 359/24