Question

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Answer 1

Explanation:

2x + y = 12 equ 1

x - y = 9 equ 2

from equ 2 make x the subject

x - y = 9

x = 9 + y equ 3

substitute equ 3 to equ 1

2x + y = 12

2(9 + y ) + y = 12

18 + 2y + y = 12

3y = - 6

y = -2

substitute y = -2 into equ 3

x = 9 + (-2)

x = 9 - 2 = 7

(x, y) = (7, -2)

let's prove and see if we are correct

2x + y = 12

input the values of (x, y) = ( 7, -2) into the question

2(7) + (-2) = 12

14 - 2 = 12

12 = 12

for the second equation

x - y = 9

Input the values of (x, y) = ( 7, -2) into the question

7 - (-2) = 9

7 + 2 = 9

9 = 9

Answer 2

x = 7

y = -2

Explanation:

Equation 1: 2x + y = 12

Equation 2: x - y = 9

Rewrite Equation 2 to make x the subject:

⇒ x = 9 + y

Substitute this into Equation 1 and solve for y:

⇒ 2(9 + y) + y = 12

⇒ 18 + 2y + y = 12

⇒ 18 + 3y = 12

⇒ 3y = -6

⇒ y = -2

Substitute found value of y into the rewritten Equation 2 and solve for x:

⇒ x = 9 + (-2)

⇒ x = 7