Commodity prices rise 40% of the time in which case profits come 15%.

Commodity prices steady 20% of the time in which case profits come 35%.

Commodity prices fall 40% of the time in which case profits come 45%

Given that profits are made, what is the probability that commodity prices, R, S, F?

Also how would a decision tree be drawn? How are the numbers determined for each one? I still do not understand decision trees.