Jonathan has 8 +10 = <<8+10=18>>18 letters in his name.

His sister has 5+10 = <<5+10=15>>15 letters in her name.

The total number of letters in their names is 18+15 = <<18+15=33>>33

# Answer

33
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
Jonathan's full name contains 8 letters for the first name and 10 letters for the surname. His sister's name has 5 letters for the first name and 10 letters for the second name. What's the total number of letters in their names?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
33
Jonathan's full name contains 8 letters for the first name and 10 letters for the surname. His sister's name has 5 letters for the first name and 10 letters for the second name. What's the total number of letters in their names?
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