This should be the math for the average win of each freespin type, when we assume you get a win on each spin on average.
0 spins -> 0 (duh)
8 spins -> 34,66 times the money.
10 spins -> 52,95 times the money.
12 spins -> 75,09 times the money.
14 spins -> 101,08 times the money.
16 spins -> 130,93 times the money.
18 spins -> 164,62 times the money.
20 spins -> 202,17 times the money.
22 spins -> 243,56 times the money.
25 spins -> 312,87 times the money.
30 spins -> 447,66 times the money.
40 spins -> 789,41 times the money.
50 spins -> 1227,44 times the money.
0 spins -> 0 (duh)
8 spins -> 34,66 times the money.
10 spins -> 52,95 times the money.
12 spins -> 75,09 times the money.
14 spins -> 101,08 times the money.
16 spins -> 130,93 times the money.
18 spins -> 164,62 times the money.
20 spins -> 202,17 times the money.
22 spins -> 243,56 times the money.
25 spins -> 312,87 times the money.
30 spins -> 447,66 times the money.
40 spins -> 789,41 times the money.
50 spins -> 1227,44 times the money.