225 (1) 10a(5a -7b)-6a(5b+7a )-3ab (2) -2b(a-2b)-b(a+4b) (3) 1,4x(0,5x+0,3y)-5(0,4y-4xy)+0,2(8y-5x) (4) 5x(6x+3y)+3y(2x-4y)-6x(5y-2x)

1) 10а * (5а^2 - 7b) - 6a * (5b + 7a^2) - 3ab = 50a^3 - 70ab - 30ab - 42a^3 - 3ab = 8a^3 - 100ab - 3ab = 8a^3 - 103ab;

2) -2b * (a^3 - 2b) - b * (a^3 + 4b^2) = -2a^3b + 4b^2 - a^3b - 4b^3 = -3a^3b + 4b^2 - 4b^3;

3) 1,4x * (0,5x + 0,3y) - 5 * (0,4y^2 - 4xy) + 0,2 * (8y - 5x) = 7x^2 + 4,2xy - 2y^2 + 20xy + 1,6y - x = 7x^2 + 24,2xy - 2y^2 + 1,6y - x;

4) 5x * (6x + 3y) + 3y * (2x - 4y) - 6x * (5y - 2x) = 30x^2 + 15xy + 6xy - 12y^2 - 30xy + 12x^2 = 42x^2 - 9xy - 12y^2;

5) 4y - 2 * (y - 3) - 3 * (y - 3 * (4 - 2y) + 8) = 4y - 2y + 6 - 3 * (y - 12 + 6y + 8) = 2y + 6 - 3y + 36 - 18y - 24 = -19y + 18.