(1/3)х+0,4х+12=х
12=х-0,4х-(1/3)х
12=0,6х-(1/3)х
12=(3/5-1/3)х
12=((9-5)/15)х
12=(4/15)х
х=12*15/4
х=45км
(1/3)х+0,4х+12=х
12=х-0,4х-(1/3)х
12=0,6х-(1/3)х
12=(3/5-1/3)х
12=((9-5)/15)х
12=(4/15)х
х=12*15/4
х=45км