Khan/khan-exercises — pull request #9266 by mwahl (2011-12-22 06:57:45+00:00)
Title: Add exercises: Fractions number line 1/2/3

Taking care of https://trello.com/card/board/fractions-and-decimals-on-a-number-line/4d87e664967a0775082939ab/4eabbc0ddec46f564d2c34b3.

@beneater - review of interactive usage would be awesome.

@elizabethslavitt - review of hints would be awesome.