Question

78×85+35×79-20×79用简便方法怎么做？

Answer 1

78×85+35×79-20×79用简便方法怎么做？
78×85＋35×79-20×79
=78×85＋(35-20)×79
=78×85＋15×79
=78×85＋15×(78＋1)
=78×85＋15×78＋15
=78×(85＋15)＋15
=78×100＋15
=7800＋15
=7815

Answer 2

这道题简便做法是:用 78×85+(35-20)×76

Answer 3

78×85＋35×79－20×79
=78×85＋(35－20)×79
=78×85＋15×79
=78×85＋15×(78＋1)
=78×85＋15×78＋15
=78×(85＋15)＋15
=78×100＋15
=7800＋15
=7815

Answer 4

79*85-85+79*35-79*20
=79（85+35-20）-85
=790-85
=705

Answer 5

78X85+35X79-20X79
=78X85+79X（35-20）
=78X85+79X15
=79X85+79X15-85
=79X（85+15）-85
=7900-85
=7815