Look at this series: 80, 10, 70, 15, 60, ... What number should come next?  Answers:
A) 20 B) 25 C) 30 D) 50 E) None
Explanation: This is an alternating addition and subtraction series. In the first pattern, 10 is subtracted from each number to arrive at the next. In the second, 5 is added to each number to arrive at the next.   20nswer: Option 20
<result>A</result>
Look at this series: 80, 10, 70, 15, 60, ... What number should come next?