[tex]\displaystyle\bf\\\log_{2}0,8-\log_{2}1\frac{1}{8} +\log_{2} 22,5=\log_{2} \frac{0,8\cdot22,5}{1,125} =\log_{2} \frac{18}{1,125} =\\\\\\=\log_{2} 16=\log_{2} 2^{4} =4\underbrace{\log_{2}2}_{1}=4\cdot 1=4[/tex]