# Algebra II : Adding and Subtracting Fractions

## Example Questions

### Example Question #71 : Adding And Subtracting Fractions

Solve:

Explanation:

In order to add or subtract the numerator, we will need common denominators.

The least common denominator is 24.

Convert the first fraction to the common denominator by multiplying both the top and bottom by 8.

Subtract the numerator only.  The denominator will remain the same.

### Example Question #72 : Adding And Subtracting Fractions

Explanation:

In order to add the fractions, we will need a common denominator.  Write out some of the factors for each of the denominators:

Notice that since  is a common denominator, we will need to change the fractions with a denominator of .

Simplify the fractions.

Reduce the fraction.

### Example Question #73 : Adding And Subtracting Fractions

Explanation:

In order to subtract, convert the second fraction to an improper fraction.

Multiply the denominator by the whole number and add the numerator.  The denominator stays the same.

Multiply the two denominators together in order to obtain the least common denominator. Convert the fractions and simplify.

### Example Question #74 : Adding And Subtracting Fractions

Sum the fractions:

Explanation:

In order to add the fractions, determine the least common denominator.

The LCD is 44 since this number is divisible by both 11 and 44.

Convert the fractions.

Add the numerator.  The denominator remains the same.

### Example Question #75 : Adding And Subtracting Fractions

Explanation:

In order to add these fractions, it is necessary to find the least common denominator.  We cannot add the numerators unless the denominators are the same,

Multiply the numerator and denominator together.

Convert the fractions.

Add the numerators. The denominators will not change.

### Example Question #76 : Adding And Subtracting Fractions

Solve:

Explanation:

To compute the sum of the fractions, we will need to determine the least common denominator.

The LCD is 20, since all this is the lowest number divisible by all the numbers of the denominators.  Convert the fractions to this denominator.

Simplify the fractions.

### Example Question #77 : Adding And Subtracting Fractions

Subtract the fractions:

Explanation:

Convert the first fraction by multiplying the top and bottom by two.

Now that the denominators are common, the numerators can be subtracted.

### Example Question #78 : Adding And Subtracting Fractions

Explanation:

The denominators are not common.  To be able to add the numerators, we will need to determine the least common denominator.

By visualization, the LCD is 40 because this is the least number that is divisible by all three of the uncommon denominators.

Convert the fractions.  Multiply the numerator by what was multiplied on the denominator to get the LCD.

### Example Question #79 : Adding And Subtracting Fractions

Explanation:

In order to add the fractions, we will need to determine the least common denominator.  Multiply the two denominators together using the FOIL method.

Convert the fractions.

Simplify the terms of the numerator.

Combine the terms as one fraction.

### Example Question #80 : Adding And Subtracting Fractions

Subtract the fractions:

Explanation:

In order to subtract the fractions, we will need a least common denominator.

Write out some factors for the two uncommon denominators.

We can convert both fractions with a common denominator of 24.

With similar denominators, we can subtract the numerators.