2/1吨=0.5吨 8/1吨=0.125吨
题意可说成:0.5吨小麦磨出0.125吨面粉.
0.125/0.5=0.25 即出面率为:25%
1/0.25=4吨 则,磨1吨面粉需4吨小麦.