a little number crunching

I got this in an email and tried it.
AND IT WORKED.
I’m one of those people who still sometimes figures on her fingers, so I’m reluctant to speculate about how it works. (But I do think it has something to do with the numbers you use to multiply, add, and subtract.)
The point of it all is that one can tell your age by your preferences for eating out. Try it. You’ll like it:

1. First of all, pick the number of times a week that you would like to
go out to eat. (More than once but less than 10)
2. Multiply this number by 2 (just to be bold)
3. Add 5
4. Multiply it by 50
5. If you have already had your birth day this year add 1757… If you haven’t, add 1756.
6. Now subtract the four digit year that you were born.
You should have a three digit number
The first digit of this is your original number. (I.e., how many times you want to go out to restaurants in a week.)
The next two numbers are YOUR AGE ! —— (Oh YES, it is!!!)
THIS IS THE ONLY YEAR (2007) IT WILL EVER WORK, SO TRY IT WHILE IT LASTS.

Who are the people who sit around and make up these things!!