## Algebra Rule 10

#### Convert a division between two fractions into a fraction of two multiplications

**Description:**

This is a combination of rule 3 and rule 4.

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**Howdy!** Here are a few very handy rules of algebra. These basic rules are useful for everything from figuring out your gas mileage to acing your next math test — or even solving equations from the far reaches of theoretical physics. *Happy calculating!*

```{({a \over c})\over({b \over d})} = {ad \over bc}```

This is a combination of rule 3 and rule 4.

```{({4 \over 5})\over({2\over1})} = {0.2 \over 2} = {4 \over 10} = {4*1 \over 2*5}```

Algebra rules is a project by two of the folks who run The Autodidacts.

A couple of autodidact math enthusiasts, we were looking for all the rules of basic algebra concisely presented in one place. We couldn’t find such a place, so we made **Algebrarules.com**

These simple rules — applied with a pinch of imagination and a dash of arithmetic — can divide, conquer, and solve just about any practical algebra problem.

If you find errata in the math, bugs in the code of Algebrarules.com, or just want to say *Eh*, please send us a letter or join us on our roost: @rulesofalgebra.