Look at this series: 15, 15, 27, 27, 39, 39,? ... What number should fill the blank?  Choose the correct choice from the following answers.
A) 51
B) 39
C) 23
D) 15
E) None
Explanation: In this simple addition with repetition series, each number in the series repeats itself, and then increases by 12 to arrive at the next number.   51nswer: Option 51
<result>A</result>
Look at this series: 15, 15, 27, 27, 39, 39,? ... What number should fill the blank?