When you see that type of handicapping, its 90% of the difference of your average and 220. So it would be 220-149=71 and then 71*.9=63.9 and since in bowling we never round up its 63.
When it comes to just 3 games where series total is the determining factor of winning some tournaments will then go with 90% of 660(220*3). So it would be 660-(149*3)=660-447=213, then 213*.9=191.7 which will be 191 and would be added to the total.
Are you sure that you can use last years average? Some tournaments may require you to use this years average at a certain date if you are 10 pins over the
book average. If you are able to use last years, make sure you score well. Good luck and high scoring.