Look at this series: 80, 10, 70, 15, 60, ... What number should come n

1.	Look at this series: 80, 10, 70, 15, 60, ... What number should come next?
Answer» 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.

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