Give the step-by-step reasoning process and then the final answer. Anna, Alison, and Jeff collect stamps. Anna had 37 stamps in her collection, Alison had 28 stamps in her collection, and Jeff had 31 stamps in his collection. Alison gave Anna half of her collection in exchange for a novel, and then Anna traded Jeff two bluebird stamps for one mountain stamp. How many stamps did Anna have in the end?
Alison gave Anna 1 / 2 * 28 = 28 / 2 = 14 stamps. Adding Alison's stamps to Anna's collection means Anna has 14 + 37 = 51 stamps. Then Anna traded Jeff 2 stamps, so she had 51 - 2 = 49 stamps. Anna got 1 stamp back in the trade, so she had 49 + 1 = 50 stamps in the end.
The final answer: 50.