Adding and subtracting fractions
Fractions can only be added or subtacted if they have the same denominator. When coming across a question where the fractions have different denominators, you must find a lowest common denominator between the two. When adding fractions, you add the numerators together and leave the denominators the same. The same rules apply for subtacting fractions(only subtact the numerators). Whatever you do to the denominators to make them the same, you must do the same to the numerators. Reduce the fractions when necessary.

Mixed Fractions; When dealing with mixed fractions, you must change the mixed fraction to improper. You do so by multiplying the whole number by the denominator and then adding the numerator. Continue with the fraction rules stated above.

Examples:
1) 3/8+1/4
=3/8+(1/4)(2) <--- multiply both numerator and denominator by 2.
=3/8+2/8 <---now add numerators ONLY
=5/8 <--final answer

2) 3/10+9/10 <--these denominators stay the same
=12/10 <--make into a mixed fraction
=1 2/10 <-- reduce
=1 1/5 <--final answer

3)1 2/10 - 4/10<--make mixed fraction improper
= 12/10- 4/10
=8/10

Practice
1) 5/6- 2/5 2) 1 7/9 - 2/5 3) 2/10+ 4/5


Videos to help better understand:
http://youtu.be/yXiG2iv1Vq8 <-- subtracting mixed fractions
http://youtu.be/t6Gz2zwmeD0 <-- adding and subtracting fractions (with word problems)
Fraction Games!!!!
http://www.math-play.com/adding-and-subtracting-fractions-game.html