The almanac, the dictionary, the biography, and the cookbook together weigh $$4310\text{g}+2325\text{g=6635g}$$. Since the almanac and the biography together weigh $$2795\text{g}$$, the cookbook and the dictionary together weigh $$6635\text{g}-2795\text{g=3840g}$$. 
There are four books on my shelf. The almanac and the dictionary together weigh $$4310\text{g}$$. The biography and the cookbook together weigh $$2325\text{g}$$. If the almanac and the biography together weigh $$2795\text{g}$$, what is the weigh of the cookbook and dictionary together? 
  - $$2620\text{g}$$ 
  - $$3270\text{g}$$ 
  - $$3840\text{g}$$ 
  - $$4100\text{g}$$ 