①.1÷3/5×2/5+2/3 =1×5/3×2/5+2/3=2/3+2/3=4/3;②.9/10×1/3-3/20=3/10-3/20=3/20;③5/12+5/4÷5/8×1/2 =5/12+5/4×8/5×1/2=5/12+1=17/12;④5÷7-1/7×3 =5/7-3/7=2/7;⑤7÷15-7/30×2 =7/15-7/15=0;⑥.1-4/7...