Develop a musical piece using the given theme and incorporating the letter-based structure provided.
X:1
L:1/8
M:4/4
K:Ador
['EAAB cBAc BAGB dBGA EAAB cBcd (3(efg)', 'eaag efge']  
X:1
L:1/8
M:4/4
K:Ador
|: EAAB cBAc | BAGB dBGA | EAAB cBcd | (3(efg) dB BA A2 :| eaag efge | dBGB AGED | eaag efga | 
 bagb a2 a2 | eaag efge | dBgd BG G2 | EAAB{d} cBcd | (3(efg) dB BA A2 ||  