Question

a
$x + 2y = 16 \\ - x + 3y = 9$
b
$3x - 1y = 20 \\ + x + 1y = 4$
c
$x + 4y = 12 \\ - x - 2y = 24$
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Answer 1

a) x + 2y= 16

-x + 3y=9

____________

5y=25

y=25/5

y=5

x + 2y = 16

x + 2.5=16

x + 10=16

x=16-10

x=6

b)3x-y=20

x+y=4

_______

4x=24

x=24/4

x=6

x+y=4

6+y=4

y=4-6

y=-2

c)x+4y=12

-x-2y=24

__________

2y=38

y=38/2

y=19

x+4y=12

x+4.19=12

x+72=12

x=12-72

x=-60