11-6 2/3-3 5/7 решите плиз я даун

Question

11-6 2/3-3 5/7 решите плиз я даун

Answer 1

11-6 2/3-3 5/7=11-6 14/21-3 15/21=10 21/21-(6 14/21+3 15/21)=

=10 21/21-9 29/21=10 21/21-10 8/21=13/21

Answer 2

(231-140-78)/21 = 13/21