Trees give more oxygen then they give up but to produce the same amount of oxygen a person consumes a day, you need around 9166 leaves or about 600 average houseplants. This equates to about 7 or 8 trees a year per person. We do have to note that it is not only trees on this planet which produce oxygen but also algae too!
Also the trees that always give off oxygen are the Peepal tree giving oxygen for a full 24 hours!
Trees are very important and many large organisations are supporting deforestation from growing by planting a tree for every one cut down or simply providing charity donations to plant a tree.