2 gamblers bet $1 each on the successive tosses of a coin. each as $6. what is the probability that

a. they break even after 6 tosses?

b. one player wins all the money on the tenth toss?

my working:

a. since there are 6 tosses and equal probability of a head and tail,

the ans should be 6 x (0.5)^6

b. in order to win all the money o the other player, he needs to win 8 games and loss 2 games, where the 10th toss have to be a win.

so, (9 choose 7) x ( 0.5)^10

but i didnt get the answer