Der Koala schläft $\frac{5}{6}\backslash frac\{5\}\{6\}$ des Tages. Dies entspricht $\frac{5}{6}\backslash frac\{5\}\{6\}$ von 24 Stunden. Das berechnest du nun so:

$\frac{5}{6}\cdot 24\text{h}=\frac{5\cdot 24}{6}\text{h}=\frac{5\cdot 4\cdot 6}{1\cdot 6}\text{h}=\frac{5\cdot 4\cdot \sout{6}}{1\cdot \sout{6}}\text{h}=\frac{5\cdot 4}{1}\text{h}=20\text{h}\backslash frac\{5\}\{6\}\backslash cdot24\; \backslash text\{h\}\; \backslash \backslash =\backslash frac\{5\backslash cdot\; 24\}\{6\}\backslash text\{h\}\backslash \backslash =\backslash frac\{5\backslash cdot4\; \backslash cdot\; 6\}\{1\backslash cdot\; 6\}\backslash text\{h\}\backslash \backslash =\backslash frac\{5\backslash cdot4\; \backslash cdot\; \backslash sout\{6\}\}\{1\backslash cdot\; \backslash sout\{6\}\}\backslash text\{h\}\backslash \backslash =\backslash frac\{5\backslash cdot4\}\{1\}\backslash text\{h\}\backslash \backslash =20\backslash text\{h\}$