Can some one answer all of these questions

9) y = - 8x

2x + 4y = 0

10) 6x + 7y = 20

y = 2x

11) - 3x - 5y = 6

y = - 3

12) 6x - 5y = 22

y = - 8

13) y = 2x

3x + 3y = - 18

14) y = 8x

-5x - 5y = 0

15) y = - 3

-5x - 3y = 14

16) y = 3x

-3x - y = - 24

For question number (9) since 2x + 4y = 0 and y = - 8x, simply substitute the second equation into the first.

2x + 4y = 2x + 4 (-8x) = 2x - 32x = - 30x = 0

so x = 0 and y = 0

For question (10)

6x + 7y = 20 and y = 2x (substitute 2x everywhere you see y in the first equation). So

6x + 7 (2x) = 20

6x + 14x = 20

20x = 20

x = 1

(now substitute 1 for x in any of the equations)

y = 2x = 2 (1) = 2

So x = 1 and y = 2

Question (11)

-3 (x) - 5y = 6 and y = - 3 so

-3 (x) - 5 (-3) = 6

-3x + 15 = 6

-3x + 15 - 6 = 0

15 - 6 = 3x

9 = 3x

3x = 9

x = 3

Question (12)

6x - 5y = 22 and y = - 8

6x - 5 (-8) = 22

6x + 40 = 22

6x = 22 - 40

6x = - 18

x = - 18/6

x = - 3

Question (13)

3x + 3y = - 18 and y = 2x

3x + 3 (2x) = - 18

3x + 6x = - 18

9x = - 18

x = - 18/9

x = - 2

Question (14)

-5x - 5y = 0 and y = 8x so

-5x - 5 (8x) = 0

-5x - 40x = 0

-45x = 0

x = 0 and y=8 (0) = 0

Question (15)

-5x - 3y = 14 and y = - 3

-5x - 3 (-3) = 14

-5x + 9 = 14

-5x + 9 - 14 = 0

9 - 14 = 5x

5x = 9 - 14

5x = - 5

x = - 5/5 = 5

Question (16)

-3x - y = - 24 and y = 3x so

-3x - (3x) = - 24

-3x - 3x = - 24

-6x = - 24

x = - 24/-6

x = 4 and if x = 4 and y = 3x, then y = 3 (4) = 12

check the calculations and make sure they are correct