Chapter 2: Limits and Continuity - Section 2.3 - The Precise Definition of a Limit - Exercises 2.3 - Page 65: 7

$\delta =0.1$

We see from the graph that in order for $f(x)$ to be within $\epsilon=0.2$ of 6, we must have $$4.9 \lt x \lt 5.1.$$ Subtracting 5 from all three sides gives $$-0.1 \lt x-5 \lt 0.1.$$ Hence for $\delta = 0.1$, $$0 \lt |x-5| \lt \delta \implies 0 \lt |f(x)-6| \lt \epsilon.$$