3.
[tex]1. \ -2x+6\cdot(3x-1) =-2x+18x-6 = 16x -6\\\\2. \ (x+7)\cdot3 - 3\cdot(8+2y) = 3x+21-24-6y = 3x-6y-3\\\\3. \ (7x+2)\cdot(3y-1)=21xy-7x+6y-2\\\\4. \ 6x\cdot(x-1)+2\cdot(-x-7) = 6x^{2}-6x-2x-14 = 6x^{2}-8x-14[/tex]
