Question

−3x−9y=18
4x+3y=12
x=?
y=?​

Answer 1

x = 6

y = -4

Explanation:

−3x−9y=18

4x+3y=12

then:

3(4x+3y) = 3(12)

3*4x + 3*3y = 36

12x + 9y = 36

-3x - 9y = 18

12x + 9y = 36

9x + 0 = 54

9x = 54

x = 54/9

x = 6

4x + 3y = 12

4*6 + 3y = 12

24 + 3y = 12

3y = 12 -24

3y = -12

y = -12/3

y = -4

Check:

-3x - 9y = 18

-3*6 - 9*-4 = 18

-18 + 36 = 18