18-(1/15+1/12)*105=18-1/15*105-1/12*105=18-7-4/35=11-4/35=381/350.4*(12-x)=1.2 12-x=3 x=96.8/x=1.7/4 6.8*4=1.7*x 4*4=x x=167-3/7-1/7÷1/4=7-3/7-4/7=7-7/7=7-1=64/9*5/11+1/9*11/5=44/45-11/45=33/45=11/15