# Fractions

## Law of fractions

*(a / b) + (c / d) = (a d + b c) / (b d) (1)*

*(a / b) (c / d) = (a c) / (b d) (2)*

*(a / b) / (c / d) = (a / b) (d / c) (3)*

*(- a / b) = - (a / b) = a / (- b) (4)*

*[(a / b) + (c / d)] / [(e / f) + ( g / h)] = ([(a / b) + (c / d)] / [(e / f) + (g / h)]) ([b d f h] / [b d f h]) *

* = [((a d) + (b c)) f h] / [((e h) + (f g)) b d] (5)*