Help with algebra 1 I don’t understand this problem .

Its the first option.

Step-by-step explanation:

y = 3x - 9 on the boundary.

Any points on this line must satisfy this equation.

Try (0, -9) and (3,0):-

-9 = 3(0) - 9 = -9 so the first point is on the boundary.

(3, 0):

0 = 3(3)  - 9

= 9 -9 = 0    so this point is on the line also.