Answer :
In this expression, you must first arrange all the elements, so that you could see where to unknowns, and where not. Then you need to add or subtract like terms. After this we get the result as below.
-7 - 8y + 1 - 2y = ?
-8y - 2y - 7 + 1 = -10y -6
-7 - 8y + 1 - 2y = ?
-8y - 2y - 7 + 1 = -10y -6
