In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.
Q: Problem: rebecca ' s annual income is $ 20 , and jimmy ' s annual income is $ 10 , . by how much must rebecca ' s annual income increase so that it constitutes 55 % of rebecca and jimmy ' s combined income ?
Options: a ) 8 , b ) 9 , c ) 7.77 , d ) 10 , e ) 11
A:
c