[tex]a) |y|=|\frac{8}{5}|=\frac{8}{5}[/tex]
[tex]b) x+y=\frac{4}{5}+\frac{8}{5}=\frac{4+8}{5}=\frac{12}{5}[/tex]
[tex]c) x-y=\frac{4}{5}-\frac{8}{5}=\frac{4-8}{5}=-\frac{4}{5}[/tex]
[tex]d) x^{2}=(\frac{4}{5})^{2}=\frac{4^{2}}{5^{2}}=\frac{16}{25}[/tex]