亲,此题考察简便运算观察这个式子,发现都有2/5所以,34x2/5+2/5x66=2/5×(34+66)=2/5×100=40望采纳,谢谢
简便计算34x2/5+2/5x66=(34+66)x2/5=100x2/5=40
34x2/5+2/5x66=2/5(34+66)=2/5 x100=2x20==40