# Operations with rational numbers

## Addition

$$\frac{a}{b}+\frac{c}{d}=\frac{ad+bc}{bd}$$

## Subtraction

$$\frac{a}{b}\xb7\frac{c}{d}=\frac{ac}{bd}$$

## Multiplication

$$\frac{a}{b}:\frac{c}{d}=\frac{ad}{bc}$$

## Division

$$\frac{a}{b}:\frac{c}{d}=\frac{ad}{bc}$$

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