合理灵活计算．7.8×0.98135.8+27.5+（62.5-35.8）12×0.25+8.8×2.59÷2.4-4.2÷2.4．

Question

合理灵活计算．
7.8×0.98                           
135.8+27.5+（62.5-35.8）
12×0.25+8.8×2.5                   
9÷2.4-4.2÷2.4．

Answer 1

（1）7.8×0.98
=7.8×（1-0.02）
=7.8-7.8×0.02
=7.8-0.156
=7.644

（2）135.8+27.5+（62.5-35.8）
=135.8+27.5+62.5-35.8
=（135.8-35.8）+（27.5+62.5）
=100+90
=190

（3）12×0.25+8.8×2.5
=12×0.25+88×0.25
=（12+88）×0.25
=100×0.25
=25

（4）9÷2.4-4.2÷2.4
=（9-4.2）÷2.4
=4.8÷2.4
=2