УМОЛЯЮ
4- ( 4 21/40 - 5,25) : 1 9/10

4 - ( 4 2140 - 5,25 ) : 1 910 =4 2976
4 2140 - 5,25 = 4 2140 - 5 14 = - (5 1040 -4 2140)= 
- ( 4 5040 - 4 2140 ) = - 2940
- 2940 : 1 910 = - 2940 :1910 =- 2940 x 1019 =-2976
4 - ( - 2976) = 4 + 2976 = 4 2976
5,25 = 5 25100 = 5 14
1 910 = 1910