Which number line shows the solution to 1/4x +1<5?

It would be an open dot on 20 going to the left.

Step-by-step explanation:

1/4x + 1 < 5

-1             -1

1/4x < 5

Divide by 1/4

x < 20

Anything less than 20 can be x. It would be an open dot on 20 going to the left (anything less than 20, ex. 19, 18, 17, 0, -1, -2, etc).

From the given steps:
Step 1: (x + y)2 - (x - y)2 = (x + y)(x + y) - (x - y)(x - y) 
Step 2: (x + y)(x + y) - (x - y)(x - y) = (x2 + xy + xy + y2) - (x2 - xy - xy + y2) 
Step 3: (x2 + xy + xy + y2) - (x2 - xy - xy + y2) = (x2 + 2xy + y2) - (x2 - 2xy + y2) 
Step 4: (x2 + 2xy + y2) - (x2 - 2xy + y2) = x2 + 2xy + y2 - x2 + 2xy - y2 
Step 5: x2 + 2xy + y2 - x2 + 2xy - y2 = 4xy 

The justification for Step 3 of her proof is:

D. Distributive property