Answer:
(2x + 3y) - (3x + y) = 5 - 18
2x + 3y - 3x - y = -13
-x + 2y = -13
we rewrite the equation by changing the signs
x- 2y = 13
solve the equation for x as a function of y
x = 13 + 2y
substitute x into one of the equations to find the value of y. For example, we'll use the equation 3x + y = 18.
3(13 + 2y) + y = 18
39 + 6y + y = 18
7y = 18 - 39
7y = -21
y = -3
we calculate x :
x = 13 + 2(-3) = 13 - 6 = 7
the coordinates of the vertex of the triangle are (7, -3)