which statement is true?

a. all quadrilateral are polygons with two pairs of parallel sides
b. all quadrilateral are polygons with four sides
c. all quadrilateral are polygons with at least one pair of parallel sides
d. all quadrilateral are polygons with four sides and at least one pair of parallel sides

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18

it would rotate about 180 degrees.