我是这样做旳.
参考下.
872×45.8÷8.72×8.72÷45.8÷8.72
=(872÷8.72)×45.8×8.72÷45.8÷8.72
=100x(45.8÷45.8)x(8.72÷8.72)
=100
西西,.
不晓得正确不,