Let x = the number of consecutive wins
54 + x = the new number of wins
78 + x = the new number of games (since she is to have no losses going forward)
(54 + x)/(78 + x) = her new percentage of wins = .75 = 3/4
Cross multiply
216 + 4x = 234 + 3x
x = 18
Take this answer and make sure it satisfies the conditions of the problem.