Can someone explain this and me write it and write the list of steps

So first we find the angle C first
Since A-C-D is a straight line, then its 180 degree
With that we can do 113-180 = 67
So angle C is 67 degree

Now as a general rule, the total of all angles in a triangle is equal to 180

So to find for angle B we can write an algebraic equation
Angle A + Angle C + Angle B = 180
Let x represent Angle B

So 
72 + 65 + x = 180
we now solved for x

X was solved to be 43 then the measure of Angle B is 43 degree