# ISEE Middle Level Quantitative : How to subtract fractions

## Example Questions

### Example Question #1 : How To Subtract Fractions

Which is the greater quantity?

(a)

(b)

(a) and (b) are equal

(b) is greater

It is impossible to tell from the information given

(a) is greater

(b) is greater

Explanation:

"Borrow" 1 from the 8 and subtract vertically:

:

### Example Question #2 : How To Subtract Fractions

Which is the greater quantity?

(a)

(b)

It is impossible to tell from the information given

(a) and (b) are equal

(a) is greater

(b) is greater

(b) is greater

Explanation:

"Borrow" 1 from the 6 and subtract vertically:

### Example Question #3 : How To Subtract Fractions

Which is the greater quantity?

(a)

(b)

(a) is greater

(b) is greater

It is impossible to tell from the information given

(a) and (b) are equal

(a) is greater

Explanation:

(a)

(b)

, so .

### Example Question #1 : How To Subtract Fractions

Which is the greater quantity?

(a)

(b)

(a) is greater

It is impossible to tell from the information given

(b) is greater

(a) and (b) are equal

(a) is greater

Explanation:

Subtract both sides of the two equations:

Since  , then

### Example Question #5 : How To Subtract Fractions

Explanation:

When subtracting fractions with different denominators, first change the fractions so that they have the same denominator. Do this by finding the least common multiple of both 4 and 8. Some multiples of 4 and 8 are:

4: 4, 8, 12, 16...

8: 8, 16, 24, 32...

Since 8 is the first common multiple between 4 and 8, change the fractions accordingly so that their denominators equal 8. Since  already has a denominator of 8, it does not need to change. Change , however, accordingly.

The problem now looks like this:

### Example Question #6 : How To Subtract Fractions

None of these

Explanation:

When dealing with fractions and mixed numbers, first convert the mixed numbers to improper fractions.

The next thing you must do is change the denominators so that they are equal. Do this by finding the least common multiple of 2 and 5. Some multiples of 2 and 5 are:

2: 2, 4, 6, 8, 10...

5: 5, 10, 15, 20...

10 is the first common multiple of both 2 and 5, so change the fractions accordingly so that their denominators both equal 10.

The problem now looks like this: