Question 132990
Let us assume that she has to play 4x games 
to make the winning percentage of 55%

Out of the 4x games played,she is supposed to win 3x games
(429+3x)/(429+431+4x)=55/100
(429+3x)/(860+4x)=11/20
8580+60x=9460+44x
60x-44x=9460-8580
16x=880

x=880/16=55

Therefore,she should play 4 x 55 or 220 more games.