  This addendum devotes to a detailed proof for the inequality (9.14) in our
joint work: Arithmetic exponent pairs for algebraic trace functions and
applications, with an appendix by Will Sawin, arXiv:1603.07060 [math.NT], which
will appear in Algebra and Number Theory. We do not intend to publish this
addendum in any journals; arXiv should be a good place for those reader who
want to find such details. The proof involves various averages of arithmetic
functions.
