4 - ( 4 21\40 - 5,25 ) : 1 9\10 =4 29\76
4 21\40 - 5,25 = 4 21\40 - 5 1\4 = - (5 10\40 -4 21\40)=
- ( 4 50\40 - 4 21\40 ) = - 29\40
- 29\40 : 1 9\10 = - 29\40 :19\10 =- 29\40 x 10\19 =-29\76
4 - ( - 29\76) = 4 + 29\76 = 4 29\76
5,25 = 5 25\100 = 5 1\4
1 9\10 = 19\10