Пожалуйста !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Решите задачу:

$( \frac{17}{10} - \frac{1}{20} )* \frac{2}{15} =( \frac{34}{20} - \frac{1}{20} )* \frac{2}{15} = \frac{33}{20} * \frac{2}{15} = \frac{11*1}{10*5} = \frac{11}{50} =0.22 \\ \\ \frac{a ^{2}-36 }{2a ^{2}+12a} = \frac{(a-6)(a+6)}{2a(a+6)} = \frac{a-6}{2a} \\ a=-0.3 \\ \frac{-0.3-6}{2*(-0.3)} = \frac{-6.3}{-0.6} =10.5$