help

Click here for the solution.

Its a great video.

Just watch from the beginning to 2:30.

In two minutes and 30 seconds you can solve this problem easily!

Let DAC  = A      EBD  = B     ACE  = C    BDA  = D     CEB   = E

Starting a the top left and  moving clock-wise, call the  interior angles  of the  interior  irregular pentagon 

  F , G, H, I , J 

The sum of these interior angles =   540°

And the sum of the angles of the five triangles abutting  this irregular pentagon =  5 * 180  = 900°

So.....the    base  angles  on the sides of the  triangles  abutting this irregular pentagon  lead to this equation

2(180 - F) + 2(180 - G)  + 2(180 - H)  + 2 (180 - I) + 2(180 - J)  +  A + B + C + D + E  = 900

Simplify

1800 -  2 ( F + G + H + I + J)  +  A + B + C + D + E  =  900

1800 - 2(540)  +  A + B + C + D + E  = 900

1800 - 1080  + A + B + C + D + E =  900

720  + A + B + C + D + E   = 900

A + B + C + D + E   =  900  -720   =   180°