Answer:
x = 2; y = 3
Explanation:
Since the quadrilateral has 4 right angles, it is a rectangle.
In a rectangle, opposite sides are congruent.
3x + y = 12 - y
x - 1 = y - x
We have a system of two equation is 2 variables.
Let's simplify both equations.
3x + 2y = 12
2x - y = 1
Rewrite the first equation. Multiply both sides of the second equation by 2. Add the equations.
3x + 2y = 12
(+) 4x - 2y = 2
-------------------------
7x = 14
Divide both sides by 2.
x = 2
Substitute 2 for x in the second original equation and solve for y.
x - 1 = y - x
2 - 1 = y - 2
1 = y - 2
y = 3
Answer: x = 2; y = 3