1、
10÷(1/2-2/5)×5
=10÷1/10×5
=100×5
=500元
2、
2÷(1/2-1/3)
=2÷1/6
=12千米
3、
5.6÷[4/5-(1-2/3)]
=5.6÷7/15
=5.6×15/7
=12吨