Answer:
The possible number that Hall could be thinking of is 144.
Step-by-step explanation:
Difference between 17 and the square root of my mystery number
This is represented by:

is 5
Then:

What are two possible numbers that Hall could be thinking of?
We have to solve the equation, for x. So




The possible number that Hall could be thinking of is 144.
Slope intercept means
y=mx+c
the slope of the line is m=(y2-y1)/(x2-x1)=(-3-5)/(1+1)= -4
the equation of the line is
y-5 = -4(x+1)
4x+y-1=0
changing the equation into slope intercept form
y= -4x+1