# Operations with rational numbers

 $\frac{a}{b}+\frac{c}{d}=\frac{ad+bc}{bd}$ Addition $\frac{a}{b}-\frac{c}{d}=\frac{ad-bc}{bd}$ Subtraction $\frac{a}{b}·\frac{c}{d}=\frac{ac}{bd}$ Multiplication $\frac{a}{b}:\frac{c}{d}=\frac{ad}{bc}$ Division
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