Question

45.6x6.7+4.56x31+0.456x20

Answer 1

原式
=45.6x6.7+45.6x3.1+45.6x0.2
=45.6x(6.7+3.1+0.2)
=45.6x(9.8+0.2)
=45.6x10
=456

供参考。

Answer 2

45.6x6.7+4.56x31+0.456x20
=45.6x(6.7+3.1+0.2)
=45.6x10
=456

追问

甲，乙二人练习跑步，甲每秒7.5米，乙每秒7米现在乙先跑10秒，甲几秒后追上乙?

追答

乙先跑10秒 =7x10=70米
甲几秒后追上乙

=70/(7.5-7)
=140秒