Adding and Subtracting Fractions

What must you have to in order to add and subtract fractions?

• common numerators

• Different numerators

• common denominators

• different denominators

What number could be a common denominator for these two fractions?
2/3   and   3/4

• 3
• 4
• 7
• 12

 $\frac{1}{5}\ and\ \frac{5}{6}$  What number could be a common denominator for these two fractions:

• 30

• 11

• 6

• 12

Find the sum.  Be sure to simplify.
-⅘ + ⅕

• -1
• -⅗
• ⅗
• 5/5

(-2/5) + (-3/5) = 

• 1
• -1
• -1/5
• 1/5

(-3/4) + 1/4 = 

• -1
• 1/2
• -1/2
• 1

4/9 + (-2/3) = 

• 1 1/9
• -1 1/9
• 2/9
• -2/9

1/4 - (3/10) = 

• 1/20
• -1/20
• 11/20
• -11/20

(-2/3) - 1/3 = 

• -1
• 1
• 1/3
• -1/3

-1 ⁷/₈ + (-3 ¹/₂)

• 5 ³/₈
• -5 ³/₈
• 1 ⁵/₈
• -1 ⁵/₈