Как это решить? *подробно*

Решите задачу:

$\frac{5 c^{2}-c }{25 c^{2}-10c+1 }+ \frac{4}{1-25 c^{2} }= \frac{c(5c-1)}{(5c-1) ^{2} }+ \frac{4}{(1-5c)(1+5c)}= \frac{c}{5c-1}- \frac{4}{(5c-1)(5c+1)} =$ $=\frac{5 c^{2}+c-4 }{(5c-1)(5c+1)}$

$1- \frac{3}{5c-1}= \frac{5c-1-3}{5c-1} = \frac{5c-4}{5c-1}$

$\frac{5 c^{2}+c-4 }{(5c-1)(5c+1)}: \frac{5c-4}{5c-1} = \frac{5(c+1)(c-0,8)*(5c-1)}{(5c-1)(5c+1)(5c-4)}= \frac{(c+1)(5c-4)}{(5c+1)(5c-4)}= \frac{c+1}{5c+1}$

$\frac{11+1}{5*11+1}= \frac{12}{56}= \frac{3}{14}$