Answer:
y = 1
x = 4
{x,y} = {4,1}
Step-by-step explanation:
[2]
x - 3y = 1
+ 3y +3y
x = 3y + 1
[1]
x + 3y = 7
(3y + 1) + 3y = 7
- 1 - 1
(3y) + 3y = 6
6y = 6
6 6
y = 1
--------------------------------
x = 3y + 1
y = 1
x = 3(1) + 1
x = 4
y = 1
x = 4
{x,y} = {4,1}