How do u simplify each expression by combining like terms?

1. 8y - 9y = -1y

( 8 - 9 = -1)

3. 8a - 6 +a - 1

( i have showed the like terms here)

8a - 1a= 7a

-6 - 1 = -7

7a - 7

5. -x - 2 + 15x

( i have showed the like terms here)

-x + 15x = 14x

(x = 1)

14x + 2

7.  8d - 4 - d - 2

( i have showed the like terms here)

8d - d = 7d

-4 -2 = -6

7d - 6

8. 9a + 8 - 2a - 3 - 5a

( i have showed the like terms here)

9a - 2a - 5a = 2a

8 - 3= 5

2a + 5

what is the answer to this

step-by-step explanation:

let pq = qr = rs = x, and xz = y and zu = z.

if the horizontal lines are parallel, then corresponding segments are in proportion:

substitute:

therefore 3 = y = z.

xu = y + z → xu = 3 + 3 = 6