-2(6-8)
-2(-2)= 4
-2(6 - 8) using distributive property
(-2 x 6) (-2 x - 8)
-12 + 16 = 4
so if she did the above step, she should get 4
the error might be that she failed to distribute to both 6 & -8 (but idk since technically idk what she did)
hope this helps