Two circles are always, never, or sometimes congruent if their radii are the equal.

always

Step-by-step explanation:

Congruent in mathematics means equal in size and shape. So, if two circles have the same radii, they are congruent, because they have the same shape (circular) and size (equal radii). The positions of them it doesn't matter, for example, they can overlap

in simplified version   it would be x ≤-4

step-by-step explanation:

multiply each term in x ≤-4 by -1

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