18. Is this figure a polygon? Explain.

no

Step-by-step explanation:

A polygon is a flat, two-dimensional shape with straight sides that is fully closed.The sides must be straight. Polygons may have any number of sides. A shape with curved sides is not a polygon.

your answer is a

step-by-step explanation:

4*4*4*4=256

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