When trying to solve for the cost of each item you will find a rainbow fish is $8.50 and a tetra is $2.50. If you use that information to solve the other answer choices C, D, and E would be correct
The owner is most likely cheating because it is usually a 50|50 chance of winning. But, you usually only get 50, and win a bit less and loose more. So, he is most likely cheating. (Hope this helped :D)