Question

How do you subtract `\frac { 2} { 3} - \frac { 1} { 5}`?

Answer 1

`7/15`

Explanation:

When adding or subtracting fractions, you must find a common denominator for both. Adding or subtracting straight across breaks math rules.

So we need to find a number that both `3` and `5` go into. The fastest way is to just multiply the two together.

`5*3=15`

Our common denominator is `15` (meaning both fractions now have a bottom of `15`). However, that is not all we do to give us the ability to subtract. When we multiplied each denominator to get `15`, we need to multiply the numerator on each fraction by the corresponding number:

`2/3 => (2(5))/(3(5)) => 10/15`

`1/5 => (1(3))/(5(3)) => 3/15`

Now that our fractions have common denominators, we can subtract. The numerators are the only ones to change.

`10/15-3/15`

`7/15`