The Portentous Puzzle of Mr Ping!

I was rummaging through my sock drawer for .. er .. socks when I came
across this mathematical thingie called THE PORTENTOUS PUZZLE OF
MR PING, with which I had apparently amused myself in the overheated
Summer of 1998.  (I had pencilled in *Summer 1998* in a corner of the
portentous notebook paper.)

Pick the number of days a week that you would like to go out for Chinese
food (or pizza or tacos or whatever).
Multiply this number by 2.
Add 5.
Multiply result by 50.

If you have already had your birthday this year, add 1748. If you haven't, add 1747.
From this number, subtract the four digit year that is your birth year.

If you followed my most explicit instructions, you should now have a THREE DIGIT number. The first digit was the original number you chose in Step 1 (how many times a week you want to go to the The Fishy Chippy!). The second 2 digits reveal your AGE (in 1998!) !!! By the Ugly Astrologers of Chaldea, is this not AMAZING ???

Note:  1998 is the only year in which this Portentous Puzzle applies.  (So sue me.)