C = Cost To Download
M = Membership Fee.
T = 0.99C + M
Now, Plug In 6 For C.
And 12.49 For M
T = 0.99 * 6 + 12.49
0.99*6 = 5.94
T = 5.94 + 12.49
5.94+12.49 = 18.43
T = 18.43.
So, If You Want To Buy 6 Games On The Website, It Will Cost $18.43
The second one I beileve is the answer to your question
He sold one half of the pie because if you do it in your head split one half into 3 and get one sixth, then that slit in two is 1 twelfth so if he sold six pieces and six is one half of twelve then you get one half.