17. In a recent l0-year period, the change in the number of visitors to U. S. national parks
was about 11,150,000 visitors.
A. What was the mean yearly change in the
number of visitors?

M∠abc=138° and m∠def=31° . which statement is true about ∠abc and ∠def ? a: the angles are neither complementary nor supplementary. b: the angles are complementary. c: the angles are supplementary.