(5/18-7/12•0.5)•5/18-2/3 помоготе до 9:30 плиз

Решите задачу:

$( \frac{5}{18} - \frac{7}{12} *0.5)* \frac{5}{18} - \frac{2}{3} =( \frac{5}{18} - \frac{7}{12} * \frac{1}{2} )* \frac{5}{18} - \frac{2}{3} =( \frac{5}{18} - \frac{7}{24} )* \frac{5}{18} - \frac{2}{3} =$ $=( \frac{20}{72} - \frac{21}{72} )* \frac{5}{18} - \frac{2}{3} = - \frac{1}{72} * \frac{5}{18} - \frac{2}{3} =- \frac{5}{1296} - \frac{2}{3}=$ $- \frac{5}{1296} - \frac{864}{1296}=- \frac{869}{1296}$