Probability question involving finding gain or loss of a game

[Milly]

I tried using $\frac{1}{13}$ x 30 + $\frac{12}{13}$ x $\frac{47}{51}$ x -10 but it didnt work.

 

[I like Serena]

I tried using $\frac{1}{13}$ x 30 + $\frac{12}{13}$ x $\frac{47}{51}$ x -10 but it didnt work.

Hi Milly! (Smile)

I believe you already have the right answer.
What makes you say that it doesn't work?

 

[Milly]

It is not the right answer. The right answer is 2/9 p

 

[I like Serena]

It is not the right answer. The right answer is 2/9 p

How do you know what the right answer is?

 

[Milly]

This is actually a past exam question. I got the answer but I don't know how to solve it.