第一题利用加法结合律把同分母的结合在一起
4/7+3/8+5/8+5/7
=(4/7+5/7)+(3/8+5/8)
=9/7+1
=16/7
第二题首先利用积的不变规律把567和56.7变成一样的,然后利用乘法分配律
1.23×567+87.7x56.7
=12.3×56.7+87.7×56.7
=56.7×(12.3+87.7)
=56.7×100
=5670
或者1.23×567+87.7×56.7
=1.23×567+8.77×567
=567×(1.23+8.77)
=567×10
=5670
4/7+3/8+5/8+5/7
=(4/7+5/7)+(3/8+5/8)
=9/7+8/8
=2又2/7
1.23×567+87.7×56.7
=12.3×56.7+87.7×56.7
=(12.3+87.7)×56.7
=100×56.7
=5670
x56.7能简便
满意就采纳吧
7分之4+8分之3+5分之8+7分之5
=(4/7+5/7)+(3/8+5/8)
=9/7+1
=2又7分之2
1.23×567+87.7x56.7
=567×(1.23+8.77)
=567×10
=5670