Subject: mathqa
Question: a gambler has won 40 % of his 30 poker games for the week so far . if , all of a sudden , his luck changes and he begins winning 70 % of the time , how many more games must he play to end up winning 60 % of all his games for the week ?
Option: 
A: 54
B: 42
C: 36
D: 60
Answer: D