All you have to do for this is take your inches (18 7/10 or 18.7) and divide it by the number of hours (12) which makes 1.56in per hour.
X intercept is when y=0
or f(x) = 0
set the f(x)'s to 0
your answer is C
x-1=0 x+1=0 x+3=0
so x= -3, -1, and 1
Answer: The best estimate for this is 52.
