Let x be the number of gains or losses.
x=9 P= 1/2 1
x=4 P= 1/2 1
x=- 1 P= 19/2 1
e(x)= 9/2 1+4/2 1- 19/2 1 =-6/2 1 =-2/7
Average loss -2/7 yuan.