increment and decrement of a number in a number range.

Question

Hi

I am trying to increment  a number  by 40 and immidiatly decrementing it  by 29. in a number range of 1 to 100 in circularly. the process need to be repete repetedly in circular motion (one increment and one decrement , to and fro) for a "x" no of times . the result should be displayed in a sequence.

Can you please help me in solving this