Add my answer to Exercise 2.51.

Included is the following file:

	Exercise_2.51.scm

Thank you!
							Lawrence R. Amlord
							   Jul 17th, 2013
							   Xi'an, China
Update my answer to Exercise 2.49.

Modified is the following file:

	Exercise_2.49.scm

Thank you!
							Lawrence R. Amlord
							   Jul 17th, 2013
							   Xi'an, China