十四分之五减二分之一乘九分之四减九分之七
=5/14-(1/2×4/9-7/9)
=5/14-(2/9+7/9)
=5/14-1
=-9/14九又九分之八+九十九又九分之八+九百九十九又九分之八+三分之一（简算）九又九分之八+九十九又九分之八+九百九十九又九分之八+三分之一=10-1/9+100-1/9+1000-1/9+1/3=1110-(1/9+1/9+1/9-1/3)=1110-(1/3-1/3)=11102.3x-2/5×3/4=1.22.3x-2/5×3/4=1.22.3x-3/10=1.22.3x=1.2+0.32.3x=1.5x=15/23