Verified answer

Пошаговое объяснение:

9 13/19-+(8 13/19-3 15/19)=12 11/19

8 13/19-3 15/19=(165-72)/19=93/19=

=4 17/19

9 13/19+4 17/19=13+(13+17)/19=13+

+30/19=14 11/19

10 4/21-(4 10/21+3 19/21)=1 17/21

4 10/21+3 19/21=7+ (10+19)/21=8 8/21

10 4/21-8 8/21=(214-176)/21=38/21=

=1 17/21