Find angle a if mde is equal to 53° and mbc is equal to 8°

So here is how we are going to answer this:
Remember that if two secants intersect in the exterior of a circle, then the measure of the angle formed is one half the difference of the measures of the intercepted arcs. So, our equation would be A = (1/2)(mDE-mBC). Now let us plug in the values.
A= 1/2(53-8)
a= 1/2(45)
A = 22.5
Therefore, the measure of angle A is 22.5 degrees.
Hope this is the answer that you are looking for. 

The answer would be b