1) 0,1c(5c^4-2c^2d-5d) = 0,1c*5c^4 - 0,1c*2c^2d - 0,1c*5d = 0,5c^5 - 0,2c^3d - 0,5cd
2) -5ab^2(5a^2-5b-4ab^2) = -5ab^2*5a^2 - 5ab^2*(-5b) - 5ab^2*(-4ab^2) = -25a^3b^2 + 25ab^3 + 20 a^2b^4
3) 0,4cd^2(-2c^3-3d-cd) = -0,4cd^2*2c^3 - 0,4cd^2*3d - 0,4cd^2cd = -0,8c^4d^2 - 1,2cd^3 - 0,4c^2d^3
4) 3n^2(-m^2-3n-5mn^2) = -3m^2n^2 - 3n^2*3n^2*5mn^2 = -3m^2n^2 - 9n^3 - 15mn^4
5) -5n(5m^4-4m^2n+2n) = -5n*5m:4 - 5n*(-4m^2n) - 5n*2n = -25m^4n + 20m^2n^2 - 10n^2 (если я скобку там поставила)