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Решите задачу:

$3a- \frac{b+15a^2}{5a-2}+ \frac{5a}{2-5a}= \frac{3a(5a-2)}{5a-2} - \frac{b+15a^2}{5a-2}- \frac{5a}{5a-2}= \\ =\frac{15a^2-6a-b-15a-5a}{5a-2} = \frac{-11a-b}{5a-2}= \frac{-11*(-0,8)-16}{5(-0,8)-2}= \frac{-7,2}{-4-2}= \frac{7,2}{6}=1,2$

$\frac{m-6n^2}{2n-1}+3n- \frac{2n}{1-2n}= \frac{m-6n^2}{2n-1}+ \frac{3n(2n-1)}{2n-1} + \frac{2n}{2n-1}= \\ =\frac{m-6n^2+ 6n^2-3n + 2n}{2n-1} = \frac{m-n}{2n-1}=\frac{12-(-3)}{2(-3)-1}=\frac{15)}{-7}=-2 \frac{1}{7}$

$\frac{3x-10y^2}{2y-3} +5y+ \frac{2x-13y}{3-2y}=\frac{3x-10y^2}{2y-3} + \frac{5y(2y-3)}{2y-3} - \frac{2x-13y}{2y-3} = \\ =\frac{3x-10y^2 + 10y^2-15y - 2x+13y}{2y-3}=\frac{x-2y}{2y-3}=\frac{14-2(-3,5)}{2(-3,5)-3}=\frac{14+7}{-7-3}=-2,1$

$\frac{m^2-n}{m-7} -m- \frac{6m}{7-m}= \frac{m^2-n}{m-7} - \frac{m(m-7)}{(m-7)} + \frac{6m}{m-7}=\frac{m^2-n - m^2+7m + 6m}{m-7} = \\ =\frac{-n +13m}{m-7}=\frac{-(-4) +13*2}{2-7}= \frac{4 +26}{-5}=- \frac{30}{5}=-6$