I need help with all 3 please

Step-by-step explanation:

x +2y = 9. (1)

x - 2y = 5. (2)

from eqn (1)

x + 2y = 9

x = 9 - 2y.

substitute x = 9 - 2y into eqn (2)

9 - 2y - 2y = 5

-4y = 5 - 9

-4y = -4

y = 1

sub y = 1 into eqn (1)

x + 2y = 9

x + 2(1) = 9

x + 2 = 9

x = 9 - 2

x = 7.

(2) x + y = 9 (1)

x - 2y = 0 (2)

from eqn (2)

x - 2y = 0

x =0 + 2y

substitute x = 2y into eqn (1)

x + y = 9

(2y) + y = 9

3y = 9

y = 3

substitute y = 3 into eqn (2)

x - 2y = 0

x - 2(3) = 0

x - 6 = 0

x = 6.

(3) 2x + 7y = 5. (1)

2x + 3y = 9. (2)

from eqn (1)

2x + 7y = 5

7y = 5 - 2x

y = (5 - 2x)/7

sub y = (5 - 2x)/7 into eqn (2)

2x + 3y = 9

2x + 3(5 - 2x)/7 = 9

2x + (15 - 6x)/7 = 9

multiply through by 7

14x + 15 - 6x = 63

14x - 6x = 63 - 15

8x = 48

x = 6

sub x = 6 into eqn (1)

2x + 7y = 5

2(6) + 7y = 5

12 + 7y = 5

7y = 5 - 12

7y = -7

y = -1

45

step-by-step explanation: