[tex](7,2)^3*(-\frac{5}{18} ):(-0,8)^3=(\frac{72}{10} )^3*(-\frac{5}{18} ):(-\frac{8}{10} )^3=(\frac{36}{5}) ^3*(-\frac{5}{18} ):(-\frac{4}{5} )^3=\frac{6^6}{5^3} *(-\frac{5}{18} ):(-\frac{4}{5} )^3=\frac{2^6*3^6}{5^3}*( -\frac{5}{3^2*2} ):(-\frac{4}{5} )^3=-\frac{2^5*3^4}{5^2} *(-\frac{5}{4} )^3=\frac{5*3^4}{2} =\frac{5*81}{2} =\frac{405}{2}[/tex]
