4.5 is the answer (which may be $4.50 since we are speaking in terms of money)
The answer to the question
Put in terms of a
b=2a
a=a
c=a-15000
2a+a+a-15000=109000
2a+a+a=124000
4a=124000
a=31000
Candidate B received 62000 votes
Mean -to-MAD ratio is the division of the Mean by the Mean Absolute Deviaion (MAD). For the set 1, mean / MAD is 10.3 / 1. 6 = 6.4375; and for the set 2, Mean / MAD is: 12.7 / 1.5 = 8.467. This is a measure of disperssion of a set of values. MAD is calculated as the sum of the absolute differences of the values and the mean.