How a bowling average is calculated
Add up the scores of all your games and divide by the number of games. Three games of 180, 201 and 165 are 546 pins: 546 ÷ 3 = 182. Handicap pins are not part of your average; only the score you bowled counts.
Leagues drop the decimals
A league average is truncated, not rounded: 1,799 pins in 9 games is 199.88, written down as 199. That one pin matters, because your handicap is worked out from the truncated average.
What you need to raise your average
The more games you have bowled, the slower your average moves. With 5,400 pins in 30 games you average 180. To reach 185 after three more games you need 185 × 33 = 6,105 pins in total, so 705 in those three games: 235 a game. Give yourself twelve games and 198 a game is enough.