Must a function that is decreasing over a given interval always be negative over that same interval? Explain. This is the question. Can someone please help explain the question and answer?

Sample Response: For a function to be decreasing over an interval, the outputs on the function are getting smaller as the inputs of the function are getting larger, but the outputs could be positive or negative. For a function to be negative over an interval, the  outputs must be negative, while the inputs could be positive or negative.

Step-by-step explanation:

It was the Response on the Edgenuity assignment.

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