How do i complete the square ?

p^2-14p=5

Find three consecutive numbers such that the sum of one-fourth the first and one-fifth the second is five less than one-seventh the third

Find the measure of the interior angles of the following regular polygons: a triangle, a quadrilateral, a pentagon, an octagon, a decagon, a 30-gon, a 50-gon, and a 100-gon.

What’s the answer ? use the picture to see the problem