Question

五分之四减(十分之七减二十分之十三)简便计算

Answer 1

4/5 - ( 7/10 - 13/20 )
= 16/20 - 14/20 + 13/20
= 16/20 - 1/20
= 15/20
= 3/4
或者
= 0.8 - 0.7 + 0.65
= 0.1 + 0.65
= 0.75
= 3/4