How do i solve this ? ? and what is the answer ? ?

Write the expression in complete factored form. 5n_(c - 3) - n(c - 3) =

The fence around a quadrilateral-shaped pasture is 3a^2+15a+9 long. three sides of the fence have the following lengths: 5a, 10a-2, a^2-7. what is the length of the fourth side of the fence?

Worth 30 points! in this diagram, both polygons are regular. what is the value, in degrees, of the sum of the measures of angles abc and abd?