Abcd is a rectangle.
work out the angle 'a' in each diagram.

Top one: Since corners of rectangles are 90 degrees, angle ABD would be 28 degrees, and angle CBE would be 41 degrees. Subtract 90 by both numbers, and the answer is 21.

Bottom one: With the same logic, angle ADE would be 38 degrees, and angle CDB would be 35. Because of that, angle a is 55 degrees (90-35=55)