Answer:
subtraction property of equality
Step-by-step explanation:
The substraction property of equality is the property that states that you can solve the value of an equality by subtracting the value that is adding up to the variable by substracting it from the other side of the equality, an example would be like this:

By substracting form both sides the value that is along the "x" you get the value of the "x".
Y=-3
Hopefully it’s right
18 is not a function because a function is when exactly ONE x value is paired with ONE y value.
19 is not a function because of the same logic for number 18
Ok so if the bird is on the top at 15 and a half then goes down six feet substrate 15 and a half from six and you get nine and half from the ground to the bird
Answer: -10x+7
Step-by-step explanation: hope this helps!