Business Math Projection shrinking X

note: I did post this a couple days again in business math but I am reposting here with more details as nobody replied and I wasn't too clear. And I think maybe this is a algebra problem.

HI

I am lost on what to do here. I know that I knew how a long time ago but i just cant remember now.

I am doing business plan projections on an excel spreadsheet.

I have 7 years of MONTHLY sales figures.

I want to use the same figures but do several different projections like what if I can do better than I expect and can do these 7 years of sales in only 5 years. or 6 years. or whatever.

So the data is simple numbers. The sales have fluctuations so they do not go in a straight line. This data is based on what an actual business did previously so it goes up and down based on seasonal sales and economic conditions, etc.

month sales amount

1 5000

2 8000

3 7000

4... 8500

and so on for 84 months (or 7 years.)

SO I can chart/graph this data and X is the months and Y is the monthly sales amount.

I need to compress the line from left to right, from 84 months to 60 months. So I need the ups and downs on the line to look the same (just compressed) but the X line will only be 60 months. The Y starting point would be the same and the Y ending point would be the same. I then need the values for the new months. (i.e. what is the new Y for the 5 month)

Is there a program that does this or is there a excel function that does this. Or what formula do I use? I am confused and I tried a couple things but they did not work out. And yet, my gut says this should be really easy to do. But college was 30 years ago and my memory is gone.

Thank you for your help and for showing pity on an "old man". :)

Fred