解:十二分之十九减(七分之五减十二分之五)等于( 9/7 )
∵已知需求出十二分之十九减(七分之五减十二分之五)等于多少
∴十二分之十九减(七分之五减十二分之五)
= 19/12 - (5/7 - 5/12)
= 19/12 - 5/7 + 5/12
= 19/12 + 5/12 - 5/7
= 24/12 - 5/7
= 2 - 5/7
= 14/7 - 5/7
= 9/7
答:十二分之十九减(七分之五减十二分之五)等于9/7