Explanation:
ABC and CBD are SUPPLEMENTARY.
...they form a straight line = 180 degrees
So 80x + 21 + 80 - x = 180 <===== solve for 'x'
79x = 79
x = 1
Now, ABE and CBD are opposite vertical angles and are therefore equal
CBD = 80 - x = 80 -1 = 79 degrees
so ABE = 79 degrees too