Adding and Subtracting Fractions

What would be the least common denominator for these two fractions?

$$\frac{7}{8}and\ \frac{1}{6}$$  

(a)  

In preparation for a picnic, Sarah made a salad with $$\frac{1}{4}$$   of a bag of iceberg lettuce and $$\frac{5}{8}$$   of a bag of romaine lettuce. How many bags of lettuce did Sarah use in all?

(a)  

Peggy made cookies. She used $$\frac{3}{4}$$  of a cup of flour and $$\frac{5}{12}$$   of a cup of sugar. How much more flour than sugar did Paula use?

(a)  

Colton and Hayley made a stir-fry for dinner. They used $$\frac{1}{6}$$   of a pound of bell peppers, $$\frac{1}{3}$$   of a pound of mushrooms, and $$\frac{1}{9}$$   of a pound of snow peas. How many pounds of vegetables did they use in the stir-fry?

(a)  

$$\frac{8}{9}-\frac{1}{3}=$$  

(a)  

How can you find a common denominator?

simplify $$\frac{15}{20}$$  

simplify   $$\frac{6}{12}$$