Adding and subtracting fractions (d)

When you add and subtract be sure that the two fractions have the same denomination, and then add/subtract the numerators. I always do cross multiplication of the two fractions to obtain the same denominators-although there are various ways to do this.

Multiplying fractions is simply straight across.

Dividing fractions:
Keep, change, flip.
Keep the first fraction the same, change the sign to its opposite (ex:division flips to multiplication), and flip the numerator and the denominator of the second fraction. Then, preform the arithmetic from your "new" problem. 

1. 13/4            5. 13/12         9. 7/12
2. 72/12         6. 1                10. 7/36
3. 1/22           7. 13/6           11. 15/14
4. 43/24        8. 19/44         12. 69/20