a=(0,75*(-4,5))^ {-2}
źródło:
a=(0,75*(-4,5))^ {-2}=(3,375)^{-2}=(3\frac{3}{8})^{-2}
=(\frac{27}{8})^{-2}=\frac{64}{729}
\frac{1}{2}*\frac{1}{a}=\frac{1}{2}*\frac{729}{64}=\frac{729}{128}=5\frac{89}{128}