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If the distance between x and 4 needs to be less than 5, then we can either
count up 5 from 4, which takes us to 9, and draw a round parenthesis there. Or
we can count down from 4 and 5, which takes us to negative 1, and we can write a
round parenthesis there as well. Any area between these two points is fine as a
value of x. Looking at this interval, this is something we definitely know how
to handle. These solutions go from negative 1 to 9, non inclusive. And we can
also write this as negative 1 is less than x is less than 9.