Can you please tell me whats the rational behind this riddle -what theory do we use

[crackpot06]

to get answer-? First of all, pick the number of days a week that you would like to eat out.
Multiply this number by 2.
Add 5.
Multiply it by 50 [I'll wait while you get the calculator].
If you haven't had your birthday this year, add 1757. If you haven't, add 1756.
Now, subtract the four digit year that you were born.
The first digit was your original number [# times you want to eat out each week]. The second two digits are your age. -
Thanks

[happpppppy6]

umm i dont know but thats pretty neat