文档介绍：???1???????1????????????????????????????3?????????????????????????????????????????8??4??3???????6???843602??????????????????????????????????????????????????????????????????????????????????????????????????????2????????2????????2??????????????6?????????????????????????????????????=???+???+??????????6????5????4???????????????????????6??4厘米5????????6?????????????????????????????????????????????????????????????????????656064485440????6?5?2+6?4?2+5?4?2=60+48+40=148??????????(6?5+6?4+5?4) ?2= (30+24+20) ?2=74?2=148(???????????148??????????????????4???3???????????????????????????4?3??????4?3?2+4??2+3??2=24+20+15=59(???????: (4×3+4×+3×) ×2=(12+10+) ?2=?2=59(????????????59????