Add my answer to Exercise 4.5.

Included is the following file:

	Exercise_4.5.scm

Thank you!
							Lawrence X. Amlord
							  Jan 16th, 2014
							  Fuzhou, China
Add my answer to Exercise 4.6.

Included is the following file:

	Exercise_4.6.scm

Thank you!
							Lawrence X. Amlord
							  Jan 16th, 2014
							  Fuzhou, China