Respuesta :

7x-(x-y) = 7x - x + y = 6x + y

9a-(2b-a) = 9a+a-2b = 10a-2b

hope it helped
Since there's a - next to the bracket, you minus everything inside of it, if there's a minus in the bracket, it turns to +
7x-(x-y) = 7x-x+y = 6x+y
9a-(2b-a) = 9a-2b+a = 10a-2b