He pays $600 for it and he is very content with this strong animal.
After a year the value of the horse has increased to $700 and he decides to sell the horse.
But already a few days later he regrets his decision to sell the beautiful horse and he buys it again.
Unfortunately he has to pay $800 to get it back so he loses $100.
After another year of owning the horse he finally decides to sell the horse for $900.
What is the overall profit the man makes?