Add my answer to Exercise 3.15.

Included are the following 2 files:

	Exercise_3.15.pdf
	Exercise_3.15.tm

Thank you!
							Lawrence X. Amlord
							  Sept 21st, 2013
							  Xi'an, China
Add my answer to Exercise 3.16.

Included are the following 2 files:

	Exercise_3.16.pdf
	Exercise_3.16.tm

Thank you!
							Lawrence X. Ammord
							  Sept 22nd, 2013
							  Xi'an, China