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.
