Question 845402
z=x*y
p=z/2
p = ½(2a + d(n-1))n
n=x-1
d=-1
a= second prize

in your example,
x=10
y=10000
z=100000
p=50000,
n=9,
d=-1,
a=5559.56
p = ½(2a + d(n-1))n