I need an equivalent expression for (7x+8y-8)-(-x-3y-6z)

Answer 1

(7x+8y-8)-(-x-3y-6z)

First subtract the terms in the second expression, recalling that subtracting a negative value is equivalent to adding a positive value:

7 x + 8 y - 8 + x +3 y + 6 z

Now combine like terms:

7 x + 8 y - 8 + x +3 y + 6 z = 8 x +11 y + 6 z - 8