Question

3x+7y=38
x+7y=36

x-5y= -7
5x-5y=5

me ajude 

Answer 1

x-5y=-7
5x-5y=5(x-1)
x-5y=-7
-5x+5y=-5
-4x=-12
4x=12
x=3

x-5y=-7
3-5y=-7
-5y=-7-3
5y=10
y=2

3x+7y=38
x+7y=36(-1)
3x+7y=38
-x-7y=-36
2x=2
x=1

x+7y=36
1+7y=36
7y=36-1
y=5

Answer 2

{3x+7y=38
{x+7y= 36 .(-1)

-x-7y= -36
3x+7y= 38
———————
2x 0 = 2
x= 2/2
x=1

x+7y= 36
1+7y= 36
7y= 36-1
7y= 35
y=35/7
y= 5
S= {1;7}

{x-5y= -7 .(-1)
{5x-5y= 5

-x+5y= 7
5x-5y= 5
——————
4x 0 = 12
x= 12/4
x= 3

x-5y= -7
3-5y= -7
-5y= -7-3
-5y= -10 .(-1)
5y= 10
y= 10/5
y= 2

S= {3;2}