Since Nathan writes 25 letters in an hour, Jacob writes 25*2 = <<25*2=50>>50 letters in an hour.

Together, they write 50+25 = <<50+25=75>>75 letters in an hour, In 10 hours, they'll write a total of 75*10 = <<10*75=750>>750 letters

# Answer

750
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Jacob can write twice as fast as Nathan. Nathan wrote 25 letters in one hour. How many letters can the two write in 10 hours together?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
750
Jacob can write twice as fast as Nathan. Nathan wrote 25 letters in one hour. How many letters can the two write in 10 hours together?
train