In each series, look for the degree and direction of change between the numbers. In other words, do the numbers increase or decrease, and by how much
Look at this series: 80, 10, 70, 15, 60, ... What number should come next?
Pick:
A) 30
B) 40
C) 20
D) 50
E) 60
C   20   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.
<result>C</result>
In each series, look for the degree and direction of change between the numbers. In other words, do the numbers increase or decrease, and by how much
Look at this series: 80, 10, 70, 15, 60, ... What number should come next?