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$(a^2)^5 = a^{2*5} = a^{10};\\a^9*a^3 = a^{9 + 3} = a^{12};\\a^{19} * (a^2)^7 = a^{19} * a^{2*7} = a^{19} * a^{14} = a^{19 + 14} = a^{33};\\(a^4)^2 : (a^2)^3 = a^{4*2} : a^{2*3} = a^{8} : a^{6} = a^{8 - 6} = a^2;\\(-2ab)^3 = (-2)^3a^3b^3 = -8a^3b^3;\\(-0,1xy^2z)^5 = (-0,1)^5x^5(y^2)^5z^5 = -0,00001x^5y^{2*5}z^5 = -0,00001x^5y^{10}z^5;\\\\\left(-\dfrac{5}{7}m^3n^4\right)^2 = \left(-\dfrac{5}{7}\right)^2(m^3)^2(n^4)^2 = \dfrac{5^2}{7^2}m^{3*2}n^{4*2} = \dfrac{25}{49}m^6n^8.$