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 80% of the time, how many more games must he play to end up winning 60% of all his games for the week?
Choose the correct choice from the following answers.
A) 20 B) 25 C) 30 D) 35 E) 40

Rationale: "let x be the number of additional games the gambler needs to play . 0.4 ( 30 ) + 0.8 x = 0.6 ( x + 30 ) 0.2 x = 6 x = 30 the answer is c ."
Answer: C