Verified Answer :

luana

\(-(x-10)=7 \ \ \ \ | omit\ the\ bracket\\\\ -x+10=7\ \ \ \ | subtract\ 10\\\\ -x=-3\ \ \ | multiply\ by\ -1\\\\ x=3\)

X=3 because -(3-10)= 7
you add the opposite of the opposite of 3 :D