HELP ME PLZZZZZZZZNZSO

HELP ME PLZZZZZZZZNZSO class=

Answer :

13
because you have to multiply your first () to -28.
then you do (5/7 - 12/7) x (-28)
after that , you do -13/28 x (-28)
and that gets you 13.
I included a picture I think that will be more helpful. I explain the steps on there too.
View image KAANTONELLI2006