Решите пожалуйста!!Срочно надо

Решите задачу:

$\displaystyle \tt a). \ \ \left(-\frac{3}{5}\cdot0,8-\frac{13}{25}\right)\cdot0,7=(-0,6\cdot0,8-0,52)\cdot0,7=\\\\{} \ \ \ =(-0,48-0,52)\cdot0,7=-1\cdot0,7=-0,7;\\\\\\b). \ \ \ (-2,6)^{2}-(-3,2)\cdot\left(-\frac{3}{8}\right)+(-6,56)=6,76-3,2\cdot0,375-6,56=\\\\{} \ \ \ \ =0,2-1,2=-1;\\\\\\c). \ \ 0,9\cdot\bigg(\frac{4}{5}\cdot(-0,2)-\frac{21}{26}\bigg)=0,9\cdot\bigg(-0,16-\frac{21}{26}\bigg)=-0,144-\frac{189}{260}=\\\\{} \ \ \ \ =-\frac{144}{1000}-\frac{189}{260}=-\frac{5661}{6500};$

$\displaystyle \tt d). \ \ 16,09-(-8,4)\cdot\bigg(-\frac{7}{12}\bigg)-(-3,7)^{2}=16,09-\frac{84}{10}\cdot\frac{7}{12}-13,69=\\\\{} \ \ =2,4-4,9=-2,5;$