LCD
posted by ALi .
I need a reveiw on how to use the LCD least common denominator
to add and subtract

Thank you for using the Jiskha Homework Help Forum. Hopefully, this will help:
http://www.helpwithfractions.com/leastcommondenominator.html 
P.S. Something here may also help:
1. http://www.lessontutor.com/sv1.html
2. http://www.math.com/school/subject1/lessons/S1U4L3DP.html 
Is 6/28 the lowest common denominator or 3/7